/*!
 * FullCalendar v2.4.0
 * Docs & License: http://fullcalendar.io/
 * (c) 2015 Adam Shaw
 */

(function(factory) {
    if (typeof define === 'function' && define.amd) {
        define([ 'jquery', 'moment' ], factory);
    }
    else if (typeof exports === 'object') { // Node/CommonJS
        module.exports = factory(require('jquery'), require('moment'));
    }
    else {
        factory(jQuery, moment);
    }
})(function($, moment) {



var fc = $.fullCalendar24 = { version: "2.4.0" };
var fcViews = fc.views = {};


$.fn.fullCalendar24 = function(options) {
    var args = Array.prototype.slice.call(arguments, 1); // for a possible method call
    var res = this; // what this function will return (this jQuery object by default)

    this.each(function(i, _element) { // loop each DOM element involved
        var element = $(_element);
        var calendar = element.data('fullCalendar'); // get the existing calendar object (if any)
        var singleRes; // the returned value of this single method call

        // a method call
        if (typeof options === 'string') {
            if (calendar && $.isFunction(calendar[options])) {
                singleRes = calendar[options].apply(calendar, args);
                if (!i) {
                    res = singleRes; // record the first method call result
                }
                if (options === 'destroy') { // for the destroy method, must remove Calendar object data
                    element.removeData('fullCalendar');
                }
            }
        }
        // a new calendar initialization
        else if (!calendar) { // don't initialize twice
            calendar = new Calendar(element, options);
            element.data('fullCalendar', calendar);
            calendar.render();
        }
    });
    
    return res;
};


var complexOptions = [ // names of options that are objects whose properties should be combined
    'header',
    'buttonText',
    'buttonIcons',
    'themeButtonIcons'
];


// Merges an array of option objects into a single object
function mergeOptions(optionObjs) {
    return mergeProps(optionObjs, complexOptions);
}


// Given options specified for the calendar's constructor, massages any legacy options into a non-legacy form.
// Converts View-Option-Hashes into the View-Specific-Options format.
function massageOverrides(input) {
    var overrides = { views: input.views || {} }; // the output. ensure a `views` hash
    var subObj;

    // iterate through all option override properties (except `views`)
    $.each(input, function(name, val) {
        if (name != 'views') {

            // could the value be a legacy View-Option-Hash?
            if (
                $.isPlainObject(val) &&
                !/(time|duration|interval)$/i.test(name) && // exclude duration options. might be given as objects
                $.inArray(name, complexOptions) == -1 // complex options aren't allowed to be View-Option-Hashes
            ) {
                subObj = null;

                // iterate through the properties of this possible View-Option-Hash value
                $.each(val, function(subName, subVal) {

                    // is the property targeting a view?
                    if (/^(month|week|day|default|basic(Week|Day)?|agenda(Week|Day)?)$/.test(subName)) {
                        if (!overrides.views[subName]) { // ensure the view-target entry exists
                            overrides.views[subName] = {};
                        }
                        overrides.views[subName][name] = subVal; // record the value in the `views` object
                    }
                    else { // a non-View-Option-Hash property
                        if (!subObj) {
                            subObj = {};
                        }
                        subObj[subName] = subVal; // accumulate these unrelated values for later
                    }
                });

                if (subObj) { // non-View-Option-Hash properties? transfer them as-is
                    overrides[name] = subObj;
                }
            }
            else {
                overrides[name] = val; // transfer normal options as-is
            }
        }
    });

    return overrides;
}



// exports
fc.intersectionToSeg = intersectionToSeg;
fc.applyAll = applyAll;
fc.debounce = debounce;
fc.isInt = isInt;
fc.htmlEscape = htmlEscape;
fc.cssToStr = cssToStr;
fc.proxy = proxy;
fc.capitaliseFirstLetter = capitaliseFirstLetter;


/* FullCalendar-specific DOM Utilities
----------------------------------------------------------------------------------------------------------------------*/


// Given the scrollbar widths of some other container, create borders/margins on rowEls in order to match the left
// and right space that was offset by the scrollbars. A 1-pixel border first, then margin beyond that.
function compensateScroll(rowEls, scrollbarWidths) {
    if (scrollbarWidths.left) {
        rowEls.css({
            'border-left-width': 1,
            'margin-left': scrollbarWidths.left - 1
        });
    }
    if (scrollbarWidths.right) {
        rowEls.css({
            'border-right-width': 1,
            'margin-right': scrollbarWidths.right - 1
        });
    }
}


// Undoes compensateScroll and restores all borders/margins
function uncompensateScroll(rowEls) {
    rowEls.css({
        'margin-left': '',
        'margin-right': '',
        'border-left-width': '',
        'border-right-width': ''
    });
}


// Make the mouse cursor express that an event is not allowed in the current area
function disableCursor() {
    $('body').addClass('fc-not-allowed');
}


// Returns the mouse cursor to its original look
function enableCursor() {
    $('body').removeClass('fc-not-allowed');
}


// Given a total available height to fill, have `els` (essentially child rows) expand to accomodate.
// By default, all elements that are shorter than the recommended height are expanded uniformly, not considering
// any other els that are already too tall. if `shouldRedistribute` is on, it considers these tall rows and 
// reduces the available height.
function distributeHeight(els, availableHeight, shouldRedistribute) {

    // *FLOORING NOTE*: we floor in certain places because zoom can give inaccurate floating-point dimensions,
    // and it is better to be shorter than taller, to avoid creating unnecessary scrollbars.

    var minOffset1 = Math.floor(availableHeight / els.length); // for non-last element
    var minOffset2 = Math.floor(availableHeight - minOffset1 * (els.length - 1)); // for last element *FLOORING NOTE*
    var flexEls = []; // elements that are allowed to expand. array of DOM nodes
    var flexOffsets = []; // amount of vertical space it takes up
    var flexHeights = []; // actual css height
    var usedHeight = 0;

    undistributeHeight(els); // give all elements their natural height

    // find elements that are below the recommended height (expandable).
    // important to query for heights in a single first pass (to avoid reflow oscillation).
    els.each(function(i, el) {
        var minOffset = i === els.length - 1 ? minOffset2 : minOffset1;
        var naturalOffset = $(el).outerHeight(true);

        if (naturalOffset < minOffset) {
            flexEls.push(el);
            flexOffsets.push(naturalOffset);
            flexHeights.push($(el).height());
        }
        else {
            // this element stretches past recommended height (non-expandable). mark the space as occupied.
            usedHeight += naturalOffset;
        }
    });

    // readjust the recommended height to only consider the height available to non-maxed-out rows.
    if (shouldRedistribute) {
        availableHeight -= usedHeight;
        minOffset1 = Math.floor(availableHeight / flexEls.length);
        minOffset2 = Math.floor(availableHeight - minOffset1 * (flexEls.length - 1)); // *FLOORING NOTE*
    }

    // assign heights to all expandable elements
    $(flexEls).each(function(i, el) {
        var minOffset = i === flexEls.length - 1 ? minOffset2 : minOffset1;
        var naturalOffset = flexOffsets[i];
        var naturalHeight = flexHeights[i];
        var newHeight = minOffset - (naturalOffset - naturalHeight); // subtract the margin/padding

        if (naturalOffset < minOffset) { // we check this again because redistribution might have changed things
            $(el).height(newHeight);
        }
    });
}


// Undoes distrubuteHeight, restoring all els to their natural height
function undistributeHeight(els) {
    els.height('');
}


// Given `els`, a jQuery set of <td> cells, find the cell with the largest natural width and set the widths of all the
// cells to be that width.
// PREREQUISITE: if you want a cell to take up width, it needs to have a single inner element w/ display:inline
function matchCellWidths(els) {
    var maxInnerWidth = 0;

    els.find('> *').each(function(i, innerEl) {
        var innerWidth = $(innerEl).outerWidth();
        if (innerWidth > maxInnerWidth) {
            maxInnerWidth = innerWidth;
        }
    });

    maxInnerWidth++; // sometimes not accurate of width the text needs to stay on one line. insurance

    els.width(maxInnerWidth);

    return maxInnerWidth;
}


// Turns a container element into a scroller if its contents is taller than the allotted height.
// Returns true if the element is now a scroller, false otherwise.
// NOTE: this method is best because it takes weird zooming dimensions into account
function setPotentialScroller(containerEl, height) {
    containerEl.height(height).addClass('fc-scroller');

    // are scrollbars needed?
    if (containerEl[0].scrollHeight - 1 > containerEl[0].clientHeight) { // !!! -1 because IE is often off-by-one :(
        return true;
    }

    unsetScroller(containerEl); // undo
    return false;
}


// Takes an element that might have been a scroller, and turns it back into a normal element.
function unsetScroller(containerEl) {
    containerEl.height('').removeClass('fc-scroller');
}


/* General DOM Utilities
----------------------------------------------------------------------------------------------------------------------*/

fc.getClientRect = getClientRect;
fc.getContentRect = getContentRect;
fc.getScrollbarWidths = getScrollbarWidths;


// borrowed from https://github.com/jquery/jquery-ui/blob/1.11.0/ui/core.js#L51
function getScrollParent(el) {
    var position = el.css('position'),
        scrollParent = el.parents().filter(function() {
            var parent = $(this);
            return (/(auto|scroll)/).test(
                parent.css('overflow') + parent.css('overflow-y') + parent.css('overflow-x')
            );
        }).eq(0);

    return position === 'fixed' || !scrollParent.length ? $(el[0].ownerDocument || document) : scrollParent;
}


// Queries the outer bounding area of a jQuery element.
// Returns a rectangle with absolute coordinates: left, right (exclusive), top, bottom (exclusive).
function getOuterRect(el) {
    var offset = el.offset();

    return {
        left: offset.left,
        right: offset.left + el.outerWidth(),
        top: offset.top,
        bottom: offset.top + el.outerHeight()
    };
}


// Queries the area within the margin/border/scrollbars of a jQuery element. Does not go within the padding.
// Returns a rectangle with absolute coordinates: left, right (exclusive), top, bottom (exclusive).
// NOTE: should use clientLeft/clientTop, but very unreliable cross-browser.
function getClientRect(el) {
    var offset = el.offset();
    var scrollbarWidths = getScrollbarWidths(el);
    var left = offset.left + getCssFloat(el, 'border-left-width') + scrollbarWidths.left;
    var top = offset.top + getCssFloat(el, 'border-top-width') + scrollbarWidths.top;

    return {
        left: left,
        right: left + el[0].clientWidth, // clientWidth includes padding but NOT scrollbars
        top: top,
        bottom: top + el[0].clientHeight // clientHeight includes padding but NOT scrollbars
    };
}


// Queries the area within the margin/border/padding of a jQuery element. Assumed not to have scrollbars.
// Returns a rectangle with absolute coordinates: left, right (exclusive), top, bottom (exclusive).
function getContentRect(el) {
    var offset = el.offset(); // just outside of border, margin not included
    var left = offset.left + getCssFloat(el, 'border-left-width') + getCssFloat(el, 'padding-left');
    var top = offset.top + getCssFloat(el, 'border-top-width') + getCssFloat(el, 'padding-top');

    return {
        left: left,
        right: left + el.width(),
        top: top,
        bottom: top + el.height()
    };
}


// Returns the computed left/right/top/bottom scrollbar widths for the given jQuery element.
// NOTE: should use clientLeft/clientTop, but very unreliable cross-browser.
function getScrollbarWidths(el) {
    var leftRightWidth = el.innerWidth() - el[0].clientWidth; // the paddings cancel out, leaving the scrollbars
    var widths = {
        left: 0,
        right: 0,
        top: 0,
        bottom: el.innerHeight() - el[0].clientHeight // the paddings cancel out, leaving the bottom scrollbar
    };

    if (getIsLeftRtlScrollbars() && el.css('direction') == 'rtl') { // is the scrollbar on the left side?
        widths.left = leftRightWidth;
    }
    else {
        widths.right = leftRightWidth;
    }

    return widths;
}


// Logic for determining if, when the element is right-to-left, the scrollbar appears on the left side

var _isLeftRtlScrollbars = null;

function getIsLeftRtlScrollbars() { // responsible for caching the computation
    if (_isLeftRtlScrollbars === null) {
        _isLeftRtlScrollbars = computeIsLeftRtlScrollbars();
    }
    return _isLeftRtlScrollbars;
}

function computeIsLeftRtlScrollbars() { // creates an offscreen test element, then removes it
    var el = $('<div><div/></div>')
        .css({
            position: 'absolute',
            top: -1000,
            left: 0,
            border: 0,
            padding: 0,
            overflow: 'scroll',
            direction: 'rtl'
        })
        .appendTo('body');
    var innerEl = el.children();
    var res = innerEl.offset().left > el.offset().left; // is the inner div shifted to accommodate a left scrollbar?
    el.remove();
    return res;
}


// Retrieves a jQuery element's computed CSS value as a floating-point number.
// If the queried value is non-numeric (ex: IE can return "medium" for border width), will just return zero.
function getCssFloat(el, prop) {
    return parseFloat(el.css(prop)) || 0;
}


// Returns a boolean whether this was a left mouse click and no ctrl key (which means right click on Mac)
function isPrimaryMouseButton(ev) {
    return ev.which == 1 && !ev.ctrlKey;
}


/* Geometry
----------------------------------------------------------------------------------------------------------------------*/

fc.intersectRects = intersectRects;

// Returns a new rectangle that is the intersection of the two rectangles. If they don't intersect, returns false
function intersectRects(rect1, rect2) {
    var res = {
        left: Math.max(rect1.left, rect2.left),
        right: Math.min(rect1.right, rect2.right),
        top: Math.max(rect1.top, rect2.top),
        bottom: Math.min(rect1.bottom, rect2.bottom)
    };

    if (res.left < res.right && res.top < res.bottom) {
        return res;
    }
    return false;
}


// Returns a new point that will have been moved to reside within the given rectangle
function constrainPoint(point, rect) {
    return {
        left: Math.min(Math.max(point.left, rect.left), rect.right),
        top: Math.min(Math.max(point.top, rect.top), rect.bottom)
    };
}


// Returns a point that is the center of the given rectangle
function getRectCenter(rect) {
    return {
        left: (rect.left + rect.right) / 2,
        top: (rect.top + rect.bottom) / 2
    };
}


// Subtracts point2's coordinates from point1's coordinates, returning a delta
function diffPoints(point1, point2) {
    return {
        left: point1.left - point2.left,
        top: point1.top - point2.top
    };
}


/* Object Ordering by Field
----------------------------------------------------------------------------------------------------------------------*/

fc.parseFieldSpecs = parseFieldSpecs;
fc.compareByFieldSpecs = compareByFieldSpecs;
fc.compareByFieldSpec = compareByFieldSpec;
fc.flexibleCompare = flexibleCompare;


function parseFieldSpecs(input) {
    var specs = [];
    var tokens = [];
    var i, token;

    if (typeof input === 'string') {
        tokens = input.split(/\s*,\s*/);
    }
    else if (typeof input === 'function') {
        tokens = [ input ];
    }
    else if ($.isArray(input)) {
        tokens = input;
    }

    for (i = 0; i < tokens.length; i++) {
        token = tokens[i];

        if (typeof token === 'string') {
            specs.push(
                token.charAt(0) == '-' ?
                    { field: token.substring(1), order: -1 } :
                    { field: token, order: 1 }
            );
        }
        else if (typeof token === 'function') {
            specs.push({ func: token });
        }
    }

    return specs;
}


function compareByFieldSpecs(obj1, obj2, fieldSpecs) {
    var i;
    var cmp;

    for (i = 0; i < fieldSpecs.length; i++) {
        cmp = compareByFieldSpec(obj1, obj2, fieldSpecs[i]);
        if (cmp) {
            return cmp;
        }
    }

    return 0;
}


function compareByFieldSpec(obj1, obj2, fieldSpec) {
    if (fieldSpec.func) {
        return fieldSpec.func(obj1, obj2);
    }
    return flexibleCompare(obj1[fieldSpec.field], obj2[fieldSpec.field]) *
        (fieldSpec.order || 1);
}


function flexibleCompare(a, b) {
    if (!a && !b) {
        return 0;
    }
    if (b == null) {
        return -1;
    }
    if (a == null) {
        return 1;
    }
    if ($.type(a) === 'string' || $.type(b) === 'string') {
        return String(a).localeCompare(String(b));
    }
    return a - b;
}


/* FullCalendar-specific Misc Utilities
----------------------------------------------------------------------------------------------------------------------*/


// Creates a basic segment with the intersection of the two ranges. Returns undefined if no intersection.
// Expects all dates to be normalized to the same timezone beforehand.
// TODO: move to date section?
function intersectionToSeg(subjectRange, constraintRange) {
    var subjectStart = subjectRange.start;
    var subjectEnd = subjectRange.end;
    var constraintStart = constraintRange.start;
    var constraintEnd = constraintRange.end;
    var segStart, segEnd;
    var isStart, isEnd;

    if (subjectEnd > constraintStart && subjectStart < constraintEnd) { // in bounds at all?

        if (subjectStart >= constraintStart) {
            segStart = subjectStart.clone();
            isStart = true;
        }
        else {
            segStart = constraintStart.clone();
            isStart =  false;
        }

        if (subjectEnd <= constraintEnd) {
            segEnd = subjectEnd.clone();
            isEnd = true;
        }
        else {
            segEnd = constraintEnd.clone();
            isEnd = false;
        }

        return {
            start: segStart,
            end: segEnd,
            isStart: isStart,
            isEnd: isEnd
        };
    }
}


/* Date Utilities
----------------------------------------------------------------------------------------------------------------------*/

fc.computeIntervalUnit = computeIntervalUnit;
fc.divideRangeByDuration = divideRangeByDuration;
fc.divideDurationByDuration = divideDurationByDuration;
fc.multiplyDuration = multiplyDuration;
fc.durationHasTime = durationHasTime;

var dayIDs = [ 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat' ];
var intervalUnits = [ 'year', 'month', 'week', 'day', 'hour', 'minute', 'second', 'millisecond' ];


// Diffs the two moments into a Duration where full-days are recorded first, then the remaining time.
// Moments will have their timezones normalized.
function diffDayTime(a, b) {
    return moment.duration({
        days: a.clone().stripTime().diff(b.clone().stripTime(), 'days'),
        ms: a.time() - b.time() // time-of-day from day start. disregards timezone
    });
}


// Diffs the two moments via their start-of-day (regardless of timezone). Produces whole-day durations.
function diffDay(a, b) {
    return moment.duration({
        days: a.clone().stripTime().diff(b.clone().stripTime(), 'days')
    });
}


// Diffs two moments, producing a duration, made of a whole-unit-increment of the given unit. Uses rounding.
function diffByUnit(a, b, unit) {
    return moment.duration(
        Math.round(a.diff(b, unit, true)), // returnFloat=true
        unit
    );
}


// Computes the unit name of the largest whole-unit period of time.
// For example, 48 hours will be "days" whereas 49 hours will be "hours".
// Accepts start/end, a range object, or an original duration object.
function computeIntervalUnit(start, end) {
    var i, unit;
    var val;

    for (i = 0; i < intervalUnits.length; i++) {
        unit = intervalUnits[i];
        val = computeRangeAs(unit, start, end);

        if (val >= 1 && isInt(val)) {
            break;
        }
    }

    return unit; // will be "milliseconds" if nothing else matches
}


// Computes the number of units (like "hours") in the given range.
// Range can be a {start,end} object, separate start/end args, or a Duration.
// Results are based on Moment's .as() and .diff() methods, so results can depend on internal handling
// of month-diffing logic (which tends to vary from version to version).
function computeRangeAs(unit, start, end) {

    if (end != null) { // given start, end
        return end.diff(start, unit, true);
    }
    else if (moment.isDuration(start)) { // given duration
        return start.as(unit);
    }
    else { // given { start, end } range object
        return start.end.diff(start.start, unit, true);
    }
}


// Intelligently divides a range (specified by a start/end params) by a duration
function divideRangeByDuration(start, end, dur) {
    var months;

    if (durationHasTime(dur)) {
        return (end - start) / dur;
    }
    months = dur.asMonths();
    if (Math.abs(months) >= 1 && isInt(months)) {
        return end.diff(start, 'months', true) / months;
    }
    return end.diff(start, 'days', true) / dur.asDays();
}


// Intelligently divides one duration by another
function divideDurationByDuration(dur1, dur2) {
    var months1, months2;

    if (durationHasTime(dur1) || durationHasTime(dur2)) {
        return dur1 / dur2;
    }
    months1 = dur1.asMonths();
    months2 = dur2.asMonths();
    if (
        Math.abs(months1) >= 1 && isInt(months1) &&
        Math.abs(months2) >= 1 && isInt(months2)
    ) {
        return months1 / months2;
    }
    return dur1.asDays() / dur2.asDays();
}


// Intelligently multiplies a duration by a number
function multiplyDuration(dur, n) {
    var months;

    if (durationHasTime(dur)) {
        return moment.duration(dur * n);
    }
    months = dur.asMonths();
    if (Math.abs(months) >= 1 && isInt(months)) {
        return moment.duration({ months: months * n });
    }
    return moment.duration({ days: dur.asDays() * n });
}


// Returns a boolean about whether the given duration has any time parts (hours/minutes/seconds/ms)
function durationHasTime(dur) {
    return Boolean(dur.hours() || dur.minutes() || dur.seconds() || dur.milliseconds());
}


function isNativeDate(input) {
    return  Object.prototype.toString.call(input) === '[object Date]' || input instanceof Date;
}


// Returns a boolean about whether the given input is a time string, like "06:40:00" or "06:00"
function isTimeString(str) {
    return /^\d+\:\d+(?:\:\d+\.?(?:\d{3})?)?$/.test(str);
}


/* Logging and Debug
----------------------------------------------------------------------------------------------------------------------*/

fc.log = function() {
    var console = window.console;

    if (console && console.log) {
        return console.log.apply(console, arguments);
    }
};

fc.warn = function() {
    var console = window.console;

    if (console && console.warn) {
        return console.warn.apply(console, arguments);
    }
    else {
        return fc.log.apply(fc, arguments);
    }
};


/* General Utilities
----------------------------------------------------------------------------------------------------------------------*/

var hasOwnPropMethod = {}.hasOwnProperty;


// Merges an array of objects into a single object.
// The second argument allows for an array of property names who's object values will be merged together.
function mergeProps(propObjs, complexProps) {
    var dest = {};
    var i, name;
    var complexObjs;
    var j, val;
    var props;

    if (complexProps) {
        for (i = 0; i < complexProps.length; i++) {
            name = complexProps[i];
            complexObjs = [];

            // collect the trailing object values, stopping when a non-object is discovered
            for (j = propObjs.length - 1; j >= 0; j--) {
                val = propObjs[j][name];

                if (typeof val === 'object') {
                    complexObjs.unshift(val);
                }
                else if (val !== undefined) {
                    dest[name] = val; // if there were no objects, this value will be used
                    break;
                }
            }

            // if the trailing values were objects, use the merged value
            if (complexObjs.length) {
                dest[name] = mergeProps(complexObjs);
            }
        }
    }

    // copy values into the destination, going from last to first
    for (i = propObjs.length - 1; i >= 0; i--) {
        props = propObjs[i];

        for (name in props) {
            if (!(name in dest)) { // if already assigned by previous props or complex props, don't reassign
                dest[name] = props[name];
            }
        }
    }

    return dest;
}


// Create an object that has the given prototype. Just like Object.create
function createObject(proto) {
    var f = function() {};
    f.prototype = proto;
    return new f();
}


function copyOwnProps(src, dest) {
    for (var name in src) {
        if (hasOwnProp(src, name)) {
            dest[name] = src[name];
        }
    }
}


// Copies over certain methods with the same names as Object.prototype methods. Overcomes an IE<=8 bug:
// https://developer.mozilla.org/en-US/docs/ECMAScript_DontEnum_attribute#JScript_DontEnum_Bug
function copyNativeMethods(src, dest) {
    var names = [ 'constructor', 'toString', 'valueOf' ];
    var i, name;

    for (i = 0; i < names.length; i++) {
        name = names[i];

        if (src[name] !== Object.prototype[name]) {
            dest[name] = src[name];
        }
    }
}


function hasOwnProp(obj, name) {
    return hasOwnPropMethod.call(obj, name);
}


// Is the given value a non-object non-function value?
function isAtomic(val) {
    return /undefined|null|boolean|number|string/.test($.type(val));
}


function applyAll(functions, thisObj, args) {
    if ($.isFunction(functions)) {
        functions = [ functions ];
    }
    if (functions) {
        var i;
        var ret;
        for (i=0; i<functions.length; i++) {
            ret = functions[i].apply(thisObj, args) || ret;
        }
        return ret;
    }
}


function firstDefined() {
    for (var i=0; i<arguments.length; i++) {
        if (arguments[i] !== undefined) {
            return arguments[i];
        }
    }
}


function htmlEscape(s) {
    return (s + '').replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/'/g, '&#039;')
        .replace(/"/g, '&quot;')
        .replace(/\n/g, '<br />');
}


function stripHtmlEntities(text) {
    return text.replace(/&.*?;/g, '');
}


// Given a hash of CSS properties, returns a string of CSS.
// Uses property names as-is (no camel-case conversion). Will not make statements for null/undefined values.
function cssToStr(cssProps) {
    var statements = [];

    $.each(cssProps, function(name, val) {
        if (val != null) {
            statements.push(name + ':' + val);
        }
    });

    return statements.join(';');
}


function capitaliseFirstLetter(str) {
    return str.charAt(0).toUpperCase() + str.slice(1);
}


function compareNumbers(a, b) { // for .sort()
    return a - b;
}


function isInt(n) {
    return n % 1 === 0;
}


// Returns a method bound to the given object context.
// Just like one of the jQuery.proxy signatures, but without the undesired behavior of treating the same method with
// different contexts as identical when binding/unbinding events.
function proxy(obj, methodName) {
    var method = obj[methodName];

    return function() {
        return method.apply(obj, arguments);
    };
}


// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds.
// https://github.com/jashkenas/underscore/blob/1.6.0/underscore.js#L714
function debounce(func, wait) {
    var timeoutId;
    var args;
    var context;
    var timestamp; // of most recent call
    var later = function() {
        var last = +new Date() - timestamp;
        if (last < wait && last > 0) {
            timeoutId = setTimeout(later, wait - last);
        }
        else {
            timeoutId = null;
            func.apply(context, args);
            if (!timeoutId) {
                context = args = null;
            }
        }
    };

    return function() {
        context = this;
        args = arguments;
        timestamp = +new Date();
        if (!timeoutId) {
            timeoutId = setTimeout(later, wait);
        }
    };
}



var ambigDateOfMonthRegex = /^\s*\d{4}-\d\d$/;
var ambigTimeOrZoneRegex =
    /^\s*\d{4}-(?:(\d\d-\d\d)|(W\d\d$)|(W\d\d-\d)|(\d\d\d))((T| )(\d\d(:\d\d(:\d\d(\.\d+)?)?)?)?)?$/;
var newMomentProto = moment.fn; // where we will attach our new methods
var oldMomentProto = $.extend({}, newMomentProto); // copy of original moment methods
var allowValueOptimization;
var setUTCValues; // function defined below
var setLocalValues; // function defined below


// Creating
// -------------------------------------------------------------------------------------------------

// Creates a new moment, similar to the vanilla moment(...) constructor, but with
// extra features (ambiguous time, enhanced formatting). When given an existing moment,
// it will function as a clone (and retain the zone of the moment). Anything else will
// result in a moment in the local zone.
fc.moment = function() {
    return makeMoment(arguments);
};

// Sames as fc.moment, but forces the resulting moment to be in the UTC timezone.
fc.moment.utc = function() {
    var mom = makeMoment(arguments, true);

    // Force it into UTC because makeMoment doesn't guarantee it
    // (if given a pre-existing moment for example)
    if (mom.hasTime()) { // don't give ambiguously-timed moments a UTC zone
        mom.utc();
    }

    return mom;
};

// Same as fc.moment, but when given an ISO8601 string, the timezone offset is preserved.
// ISO8601 strings with no timezone offset will become ambiguously zoned.
fc.moment.parseZone = function() {
    return makeMoment(arguments, true, true);
};

// Builds an enhanced moment from args. When given an existing moment, it clones. When given a
// native Date, or called with no arguments (the current time), the resulting moment will be local.
// Anything else needs to be "parsed" (a string or an array), and will be affected by:
//    parseAsUTC - if there is no zone information, should we parse the input in UTC?
//    parseZone - if there is zone information, should we force the zone of the moment?
function makeMoment(args, parseAsUTC, parseZone) {
    var input = args[0];
    var isSingleString = args.length == 1 && typeof input === 'string';
    var isAmbigTime;
    var isAmbigZone;
    var ambigMatch;
    var mom;

    if (moment.isMoment(input)) {
        mom = moment.apply(null, args); // clone it
        transferAmbigs(input, mom); // the ambig flags weren't transfered with the clone
    }
    else if (isNativeDate(input) || input === undefined) {
        mom = moment.apply(null, args); // will be local
    }
    else { // "parsing" is required
        isAmbigTime = false;
        isAmbigZone = false;

        if (isSingleString) {
            if (ambigDateOfMonthRegex.test(input)) {
                // accept strings like '2014-05', but convert to the first of the month
                input += '-01';
                args = [ input ]; // for when we pass it on to moment's constructor
                isAmbigTime = true;
                isAmbigZone = true;
            }
            else if ((ambigMatch = ambigTimeOrZoneRegex.exec(input))) {
                isAmbigTime = !ambigMatch[5]; // no time part?
                isAmbigZone = true;
            }
        }
        else if ($.isArray(input)) {
            // arrays have no timezone information, so assume ambiguous zone
            isAmbigZone = true;
        }
        // otherwise, probably a string with a format

        if (parseAsUTC || isAmbigTime) {
            mom = moment.utc.apply(moment, args);
        }
        else {
            mom = moment.apply(null, args);
        }

        if (isAmbigTime) {
            mom._ambigTime = true;
            mom._ambigZone = true; // ambiguous time always means ambiguous zone
        }
        else if (parseZone) { // let's record the inputted zone somehow
            if (isAmbigZone) {
                mom._ambigZone = true;
            }
            else if (isSingleString) {
                if (mom.utcOffset) {
                    mom.utcOffset(input); // if not a valid zone, will assign UTC
                }
                else {
                    mom.zone(input); // for moment-pre-2.9
                }
            }
        }
    }

    mom._fullCalendar = true; // flag for extended functionality

    return mom;
}


// A clone method that works with the flags related to our enhanced functionality.
// In the future, use moment.momentProperties
newMomentProto.clone = function() {
    var mom = oldMomentProto.clone.apply(this, arguments);

    // these flags weren't transfered with the clone
    transferAmbigs(this, mom);
    if (this._fullCalendar) {
        mom._fullCalendar = true;
    }

    return mom;
};


// Week Number
// -------------------------------------------------------------------------------------------------


// Returns the week number, considering the locale's custom week number calcuation
// `weeks` is an alias for `week`
newMomentProto.week = newMomentProto.weeks = function(input) {
    var weekCalc = (this._locale || this._lang) // works pre-moment-2.8
        ._fullCalendar_weekCalc;

    if (input == null && typeof weekCalc === 'function') { // custom function only works for getter
        return weekCalc(this);
    }
    else if (weekCalc === 'ISO') {
        return oldMomentProto.isoWeek.apply(this, arguments); // ISO getter/setter
    }

    return oldMomentProto.week.apply(this, arguments); // local getter/setter
};


// Time-of-day
// -------------------------------------------------------------------------------------------------

// GETTER
// Returns a Duration with the hours/minutes/seconds/ms values of the moment.
// If the moment has an ambiguous time, a duration of 00:00 will be returned.
//
// SETTER
// You can supply a Duration, a Moment, or a Duration-like argument.
// When setting the time, and the moment has an ambiguous time, it then becomes unambiguous.
newMomentProto.time = function(time) {

    // Fallback to the original method (if there is one) if this moment wasn't created via FullCalendar.
    // `time` is a generic enough method name where this precaution is necessary to avoid collisions w/ other plugins.
    if (!this._fullCalendar) {
        return oldMomentProto.time.apply(this, arguments);
    }

    if (time == null) { // getter
        return moment.duration({
            hours: this.hours(),
            minutes: this.minutes(),
            seconds: this.seconds(),
            milliseconds: this.milliseconds()
        });
    }
    else { // setter

        this._ambigTime = false; // mark that the moment now has a time

        if (!moment.isDuration(time) && !moment.isMoment(time)) {
            time = moment.duration(time);
        }

        // The day value should cause overflow (so 24 hours becomes 00:00:00 of next day).
        // Only for Duration times, not Moment times.
        var dayHours = 0;
        if (moment.isDuration(time)) {
            dayHours = Math.floor(time.asDays()) * 24;
        }

        // We need to set the individual fields.
        // Can't use startOf('day') then add duration. In case of DST at start of day.
        return this.hours(dayHours + time.hours())
            .minutes(time.minutes())
            .seconds(time.seconds())
            .milliseconds(time.milliseconds());
    }
};

// Converts the moment to UTC, stripping out its time-of-day and timezone offset,
// but preserving its YMD. A moment with a stripped time will display no time
// nor timezone offset when .format() is called.
newMomentProto.stripTime = function() {
    var a;

    if (!this._ambigTime) {

        // get the values before any conversion happens
        a = this.toArray(); // array of y/m/d/h/m/s/ms

        // TODO: use keepLocalTime in the future
        this.utc(); // set the internal UTC flag (will clear the ambig flags)
        setUTCValues(this, a.slice(0, 3)); // set the year/month/date. time will be zero

        // Mark the time as ambiguous. This needs to happen after the .utc() call, which might call .utcOffset(),
        // which clears all ambig flags. Same with setUTCValues with moment-timezone.
        this._ambigTime = true;
        this._ambigZone = true; // if ambiguous time, also ambiguous timezone offset
    }

    return this; // for chaining
};

// Returns if the moment has a non-ambiguous time (boolean)
newMomentProto.hasTime = function() {
    return !this._ambigTime;
};


// Timezone
// -------------------------------------------------------------------------------------------------

// Converts the moment to UTC, stripping out its timezone offset, but preserving its
// YMD and time-of-day. A moment with a stripped timezone offset will display no
// timezone offset when .format() is called.
// TODO: look into Moment's keepLocalTime functionality
newMomentProto.stripZone = function() {
    var a, wasAmbigTime;

    if (!this._ambigZone) {

        // get the values before any conversion happens
        a = this.toArray(); // array of y/m/d/h/m/s/ms
        wasAmbigTime = this._ambigTime;

        this.utc(); // set the internal UTC flag (might clear the ambig flags, depending on Moment internals)
        setUTCValues(this, a); // will set the year/month/date/hours/minutes/seconds/ms

        // the above call to .utc()/.utcOffset() unfortunately might clear the ambig flags, so restore
        this._ambigTime = wasAmbigTime || false;

        // Mark the zone as ambiguous. This needs to happen after the .utc() call, which might call .utcOffset(),
        // which clears the ambig flags. Same with setUTCValues with moment-timezone.
        this._ambigZone = true;
    }

    return this; // for chaining
};

// Returns of the moment has a non-ambiguous timezone offset (boolean)
newMomentProto.hasZone = function() {
    return !this._ambigZone;
};


// this method implicitly marks a zone
newMomentProto.local = function() {
    var a = this.toArray(); // year,month,date,hours,minutes,seconds,ms as an array
    var wasAmbigZone = this._ambigZone;

    oldMomentProto.local.apply(this, arguments);

    // ensure non-ambiguous
    // this probably already happened via local() -> utcOffset(), but don't rely on Moment's internals
    this._ambigTime = false;
    this._ambigZone = false;

    if (wasAmbigZone) {
        // If the moment was ambiguously zoned, the date fields were stored as UTC.
        // We want to preserve these, but in local time.
        // TODO: look into Moment's keepLocalTime functionality
        setLocalValues(this, a);
    }

    return this; // for chaining
};


// implicitly marks a zone
newMomentProto.utc = function() {
    oldMomentProto.utc.apply(this, arguments);

    // ensure non-ambiguous
    // this probably already happened via utc() -> utcOffset(), but don't rely on Moment's internals
    this._ambigTime = false;
    this._ambigZone = false;

    return this;
};


// methods for arbitrarily manipulating timezone offset.
// should clear time/zone ambiguity when called.
$.each([
    'zone', // only in moment-pre-2.9. deprecated afterwards
    'utcOffset'
], function(i, name) {
    if (oldMomentProto[name]) { // original method exists?

        // this method implicitly marks a zone (will probably get called upon .utc() and .local())
        newMomentProto[name] = function(tzo) {

            if (tzo != null) { // setter
                // these assignments needs to happen before the original zone method is called.
                // I forget why, something to do with a browser crash.
                this._ambigTime = false;
                this._ambigZone = false;
            }

            return oldMomentProto[name].apply(this, arguments);
        };
    }
});


// Formatting
// -------------------------------------------------------------------------------------------------

newMomentProto.format = function() {
    if (this._fullCalendar && arguments[0]) { // an enhanced moment? and a format string provided?
        return formatDate(this, arguments[0]); // our extended formatting
    }
    if (this._ambigTime) {
        return oldMomentFormat(this, 'YYYY-MM-DD');
    }
    if (this._ambigZone) {
        return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
    }
    return oldMomentProto.format.apply(this, arguments);
};

newMomentProto.toISOString = function() {
    if (this._ambigTime) {
        return oldMomentFormat(this, 'YYYY-MM-DD');
    }
    if (this._ambigZone) {
        return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
    }
    return oldMomentProto.toISOString.apply(this, arguments);
};


// Querying
// -------------------------------------------------------------------------------------------------

// Is the moment within the specified range? `end` is exclusive.
// FYI, this method is not a standard Moment method, so always do our enhanced logic.
newMomentProto.isWithin = function(start, end) {
    var a = commonlyAmbiguate([ this, start, end ]);
    return a[0] >= a[1] && a[0] < a[2];
};

// When isSame is called with units, timezone ambiguity is normalized before the comparison happens.
// If no units specified, the two moments must be identically the same, with matching ambig flags.
newMomentProto.isSame = function(input, units) {
    var a;

    // only do custom logic if this is an enhanced moment
    if (!this._fullCalendar) {
        return oldMomentProto.isSame.apply(this, arguments);
    }

    if (units) {
        a = commonlyAmbiguate([ this, input ], true); // normalize timezones but don't erase times
        return oldMomentProto.isSame.call(a[0], a[1], units);
    }
    else {
        input = fc.moment.parseZone(input); // normalize input
        return oldMomentProto.isSame.call(this, input) &&
            Boolean(this._ambigTime) === Boolean(input._ambigTime) &&
            Boolean(this._ambigZone) === Boolean(input._ambigZone);
    }
};

// Make these query methods work with ambiguous moments
$.each([
    'isBefore',
    'isAfter'
], function(i, methodName) {
    newMomentProto[methodName] = function(input, units) {
        var a;

        // only do custom logic if this is an enhanced moment
        if (!this._fullCalendar) {
            return oldMomentProto[methodName].apply(this, arguments);
        }

        a = commonlyAmbiguate([ this, input ]);
        return oldMomentProto[methodName].call(a[0], a[1], units);
    };
});


// Misc Internals
// -------------------------------------------------------------------------------------------------

// given an array of moment-like inputs, return a parallel array w/ moments similarly ambiguated.
// for example, of one moment has ambig time, but not others, all moments will have their time stripped.
// set `preserveTime` to `true` to keep times, but only normalize zone ambiguity.
// returns the original moments if no modifications are necessary.
function commonlyAmbiguate(inputs, preserveTime) {
    var anyAmbigTime = false;
    var anyAmbigZone = false;
    var len = inputs.length;
    var moms = [];
    var i, mom;

    // parse inputs into real moments and query their ambig flags
    for (i = 0; i < len; i++) {
        mom = inputs[i];
        if (!moment.isMoment(mom)) {
            mom = fc.moment.parseZone(mom);
        }
        anyAmbigTime = anyAmbigTime || mom._ambigTime;
        anyAmbigZone = anyAmbigZone || mom._ambigZone;
        moms.push(mom);
    }

    // strip each moment down to lowest common ambiguity
    // use clones to avoid modifying the original moments
    for (i = 0; i < len; i++) {
        mom = moms[i];
        if (!preserveTime && anyAmbigTime && !mom._ambigTime) {
            moms[i] = mom.clone().stripTime();
        }
        else if (anyAmbigZone && !mom._ambigZone) {
            moms[i] = mom.clone().stripZone();
        }
    }

    return moms;
}

// Transfers all the flags related to ambiguous time/zone from the `src` moment to the `dest` moment
// TODO: look into moment.momentProperties for this.
function transferAmbigs(src, dest) {
    if (src._ambigTime) {
        dest._ambigTime = true;
    }
    else if (dest._ambigTime) {
        dest._ambigTime = false;
    }

    if (src._ambigZone) {
        dest._ambigZone = true;
    }
    else if (dest._ambigZone) {
        dest._ambigZone = false;
    }
}


// Sets the year/month/date/etc values of the moment from the given array.
// Inefficient because it calls each individual setter.
function setMomentValues(mom, a) {
    mom.year(a[0] || 0)
        .month(a[1] || 0)
        .date(a[2] || 0)
        .hours(a[3] || 0)
        .minutes(a[4] || 0)
        .seconds(a[5] || 0)
        .milliseconds(a[6] || 0);
}

// Can we set the moment's internal date directly?
allowValueOptimization = '_d' in moment() && 'updateOffset' in moment;

// Utility function. Accepts a moment and an array of the UTC year/month/date/etc values to set.
// Assumes the given moment is already in UTC mode.
setUTCValues = allowValueOptimization ? function(mom, a) {
    // simlate what moment's accessors do
    mom._d.setTime(Date.UTC.apply(Date, a));
    moment.updateOffset(mom, false); // keepTime=false
} : setMomentValues;

// Utility function. Accepts a moment and an array of the local year/month/date/etc values to set.
// Assumes the given moment is already in local mode.
setLocalValues = allowValueOptimization ? function(mom, a) {
    // simlate what moment's accessors do
    mom._d.setTime(+new Date( // FYI, there is now way to apply an array of args to a constructor
        a[0] || 0,
        a[1] || 0,
        a[2] || 0,
        a[3] || 0,
        a[4] || 0,
        a[5] || 0,
        a[6] || 0
    ));
    moment.updateOffset(mom, false); // keepTime=false
} : setMomentValues;



// Single Date Formatting
// -------------------------------------------------------------------------------------------------


// call this if you want Moment's original format method to be used
function oldMomentFormat(mom, formatStr) {
    return oldMomentProto.format.call(mom, formatStr); // oldMomentProto defined in moment-ext.js
}


// Formats `date` with a Moment formatting string, but allow our non-zero areas and
// additional token.
function formatDate(date, formatStr) {
    return formatDateWithChunks(date, getFormatStringChunks(formatStr));
}


function formatDateWithChunks(date, chunks) {
    var s = '';
    var i;

    for (i=0; i<chunks.length; i++) {
        s += formatDateWithChunk(date, chunks[i]);
    }

    return s;
}


// addition formatting tokens we want recognized
var tokenOverrides = {
    t: function(date) { // "a" or "p"
        return oldMomentFormat(date, 'a').charAt(0);
    },
    T: function(date) { // "A" or "P"
        return oldMomentFormat(date, 'A').charAt(0);
    }
};


function formatDateWithChunk(date, chunk) {
    var token;
    var maybeStr;

    if (typeof chunk === 'string') { // a literal string
        return chunk;
    }
    else if ((token = chunk.token)) { // a token, like "YYYY"
        if (tokenOverrides[token]) {
            return tokenOverrides[token](date); // use our custom token
        }
        return oldMomentFormat(date, token);
    }
    else if (chunk.maybe) { // a grouping of other chunks that must be non-zero
        maybeStr = formatDateWithChunks(date, chunk.maybe);
        if (maybeStr.match(/[1-9]/)) {
            return maybeStr;
        }
    }

    return '';
}


// Date Range Formatting
// -------------------------------------------------------------------------------------------------
// TODO: make it work with timezone offset

// Using a formatting string meant for a single date, generate a range string, like
// "Sep 2 - 9 2013", that intelligently inserts a separator where the dates differ.
// If the dates are the same as far as the format string is concerned, just return a single
// rendering of one date, without any separator.
function formatRange(date1, date2, formatStr, separator, isRTL) {
    var localeData;

    date1 = fc.moment.parseZone(date1);
    date2 = fc.moment.parseZone(date2);

    localeData = (date1.localeData || date1.lang).call(date1); // works with moment-pre-2.8

    // Expand localized format strings, like "LL" -> "MMMM D YYYY"
    formatStr = localeData.longDateFormat(formatStr) || formatStr;
    // BTW, this is not important for `formatDate` because it is impossible to put custom tokens
    // or non-zero areas in Moment's localized format strings.

    separator = separator || ' - ';

    return formatRangeWithChunks(
        date1,
        date2,
        getFormatStringChunks(formatStr),
        separator,
        isRTL
    );
}
fc.formatRange = formatRange; // expose


function formatRangeWithChunks(date1, date2, chunks, separator, isRTL) {
    var chunkStr; // the rendering of the chunk
    var leftI;
    var leftStr = '';
    var rightI;
    var rightStr = '';
    var middleI;
    var middleStr1 = '';
    var middleStr2 = '';
    var middleStr = '';

    // Start at the leftmost side of the formatting string and continue until you hit a token
    // that is not the same between dates.
    for (leftI=0; leftI<chunks.length; leftI++) {
        chunkStr = formatSimilarChunk(date1, date2, chunks[leftI]);
        if (chunkStr === false) {
            break;
        }
        leftStr += chunkStr;
    }

    // Similarly, start at the rightmost side of the formatting string and move left
    for (rightI=chunks.length-1; rightI>leftI; rightI--) {
        chunkStr = formatSimilarChunk(date1, date2, chunks[rightI]);
        if (chunkStr === false) {
            break;
        }
        rightStr = chunkStr + rightStr;
    }

    // The area in the middle is different for both of the dates.
    // Collect them distinctly so we can jam them together later.
    for (middleI=leftI; middleI<=rightI; middleI++) {
        middleStr1 += formatDateWithChunk(date1, chunks[middleI]);
        middleStr2 += formatDateWithChunk(date2, chunks[middleI]);
    }

    if (middleStr1 || middleStr2) {
        if (isRTL) {
            middleStr = middleStr2 + separator + middleStr1;
        }
        else {
            middleStr = middleStr1 + separator + middleStr2;
        }
    }

    return leftStr + middleStr + rightStr;
}


var similarUnitMap = {
    Y: 'year',
    M: 'month',
    D: 'day', // day of month
    d: 'day', // day of week
    // prevents a separator between anything time-related...
    A: 'second', // AM/PM
    a: 'second', // am/pm
    T: 'second', // A/P
    t: 'second', // a/p
    H: 'second', // hour (24)
    h: 'second', // hour (12)
    m: 'second', // minute
    s: 'second' // second
};
// TODO: week maybe?


// Given a formatting chunk, and given that both dates are similar in the regard the
// formatting chunk is concerned, format date1 against `chunk`. Otherwise, return `false`.
function formatSimilarChunk(date1, date2, chunk) {
    var token;
    var unit;

    if (typeof chunk === 'string') { // a literal string
        return chunk;
    }
    else if ((token = chunk.token)) {
        unit = similarUnitMap[token.charAt(0)];
        // are the dates the same for this unit of measurement?
        if (unit && date1.isSame(date2, unit)) {
            return oldMomentFormat(date1, token); // would be the same if we used `date2`
            // BTW, don't support custom tokens
        }
    }

    return false; // the chunk is NOT the same for the two dates
    // BTW, don't support splitting on non-zero areas
}


// Chunking Utils
// -------------------------------------------------------------------------------------------------


var formatStringChunkCache = {};


function getFormatStringChunks(formatStr) {
    if (formatStr in formatStringChunkCache) {
        return formatStringChunkCache[formatStr];
    }
    return (formatStringChunkCache[formatStr] = chunkFormatString(formatStr));
}


// Break the formatting string into an array of chunks
function chunkFormatString(formatStr) {
    var chunks = [];
    var chunker = /\[([^\]]*)\]|\(([^\)]*)\)|(LTS|LT|(\w)\4*o?)|([^\w\[\(]+)/g; // TODO: more descrimination
    var match;

    while ((match = chunker.exec(formatStr))) {
        if (match[1]) { // a literal string inside [ ... ]
            chunks.push(match[1]);
        }
        else if (match[2]) { // non-zero formatting inside ( ... )
            chunks.push({ maybe: chunkFormatString(match[2]) });
        }
        else if (match[3]) { // a formatting token
            chunks.push({ token: match[3] });
        }
        else if (match[5]) { // an unenclosed literal string
            chunks.push(match[5]);
        }
    }

    return chunks;
}



fc.Class = Class; // export

// class that all other classes will inherit from
function Class() { }

// called upon a class to create a subclass
Class.extend = function(members) {
    var superClass = this;
    var subClass;

    members = members || {};

    // ensure a constructor for the subclass, forwarding all arguments to the super-constructor if it doesn't exist
    if (hasOwnProp(members, 'constructor')) {
        subClass = members.constructor;
    }
    if (typeof subClass !== 'function') {
        subClass = members.constructor = function() {
            superClass.apply(this, arguments);
        };
    }

    // build the base prototype for the subclass, which is an new object chained to the superclass's prototype
    subClass.prototype = createObject(superClass.prototype);

    // copy each member variable/method onto the the subclass's prototype
    copyOwnProps(members, subClass.prototype);
    copyNativeMethods(members, subClass.prototype); // hack for IE8

    // copy over all class variables/methods to the subclass, such as `extend` and `mixin`
    copyOwnProps(superClass, subClass);

    return subClass;
};

// adds new member variables/methods to the class's prototype.
// can be called with another class, or a plain object hash containing new members.
Class.mixin = function(members) {
    copyOwnProps(members.prototype || members, this.prototype); // TODO: copyNativeMethods?
};


var Emitter = fc.Emitter = Class.extend({

    callbackHash: null,


    on: function(name, callback) {
        this.getCallbacks(name).add(callback);
        return this; // for chaining
    },


    off: function(name, callback) {
        this.getCallbacks(name).remove(callback);
        return this; // for chaining
    },


    trigger: function(name) { // args...
        var args = Array.prototype.slice.call(arguments, 1);

        this.triggerWith(name, this, args);

        return this; // for chaining
    },


    triggerWith: function(name, context, args) {
        var callbacks = this.getCallbacks(name);

        callbacks.fireWith(context, args);

        return this; // for chaining
    },


    getCallbacks: function(name) {
        var callbacks;

        if (!this.callbackHash) {
            this.callbackHash = {};
        }

        callbacks = this.callbackHash[name];
        if (!callbacks) {
            callbacks = this.callbackHash[name] = $.Callbacks();
        }

        return callbacks;
    }

});


/* A rectangular panel that is absolutely positioned over other content
------------------------------------------------------------------------------------------------------------------------
Options:
    - className (string)
    - content (HTML string or jQuery element set)
    - parentEl
    - top
    - left
    - right (the x coord of where the right edge should be. not a "CSS" right)
    - autoHide (boolean)
    - show (callback)
    - hide (callback)
*/

var Popover = Class.extend({

    isHidden: true,
    options: null,
    el: null, // the container element for the popover. generated by this object
    documentMousedownProxy: null, // document mousedown handler bound to `this`
    margin: 10, // the space required between the popover and the edges of the scroll container


    constructor: function(options) {
        this.options = options || {};
    },


    // Shows the popover on the specified position. Renders it if not already
    show: function() {
        if (this.isHidden) {
            if (!this.el) {
                this.render();
            }
            this.el.show();
            this.position();
            this.isHidden = false;
            this.trigger('show');
        }
    },


    // Hides the popover, through CSS, but does not remove it from the DOM
    hide: function() {
        if (!this.isHidden) {
            this.el.hide();
            this.isHidden = true;
            this.trigger('hide');
        }
    },


    // Creates `this.el` and renders content inside of it
    render: function() {
        var _this = this;
        var options = this.options;

        this.el = $('<div class="fc-popover"/>')
            .addClass(options.className || '')
            .css({
                // position initially to the top left to avoid creating scrollbars
                top: 0,
                left: 0
            })
            .append(options.content)
            .appendTo(options.parentEl);

        // when a click happens on anything inside with a 'fc-close' className, hide the popover
        this.el.on('click', '.fc-close', function() {
            _this.hide();
        });

        if (options.autoHide) {
            $(document).on('mousedown', this.documentMousedownProxy = proxy(this, 'documentMousedown'));
        }
    },


    // Triggered when the user clicks *anywhere* in the document, for the autoHide feature
    documentMousedown: function(ev) {
        // only hide the popover if the click happened outside the popover
        if (this.el && !$(ev.target).closest(this.el).length) {
            this.hide();
        }
    },


    // Hides and unregisters any handlers
    removeElement: function() {
        this.hide();

        if (this.el) {
            this.el.remove();
            this.el = null;
        }

        $(document).off('mousedown', this.documentMousedownProxy);
    },


    // Positions the popover optimally, using the top/left/right options
    position: function() {
        var options = this.options;
        var origin = this.el.offsetParent().offset();
        var width = this.el.outerWidth();
        var height = this.el.outerHeight();
        var windowEl = $(window);
        var viewportEl = getScrollParent(this.el);
        var viewportTop;
        var viewportLeft;
        var viewportOffset;
        var top; // the "position" (not "offset") values for the popover
        var left; //

        // compute top and left
        top = options.top || 0;
        if (options.left !== undefined) {
            left = options.left;
        }
        else if (options.right !== undefined) {
            left = options.right - width; // derive the left value from the right value
        }
        else {
            left = 0;
        }

        if (viewportEl.is(window) || viewportEl.is(document)) { // normalize getScrollParent's result
            viewportEl = windowEl;
            viewportTop = 0; // the window is always at the top left
            viewportLeft = 0; // (and .offset() won't work if called here)
        }
        else {
            viewportOffset = viewportEl.offset();
            viewportTop = viewportOffset.top;
            viewportLeft = viewportOffset.left;
        }

        // if the window is scrolled, it causes the visible area to be further down
        viewportTop += windowEl.scrollTop();
        viewportLeft += windowEl.scrollLeft();

        // constrain to the view port. if constrained by two edges, give precedence to top/left
        if (options.viewportConstrain !== false) {
            top = Math.min(top, viewportTop + viewportEl.outerHeight() - height - this.margin);
            top = Math.max(top, viewportTop + this.margin);
            left = Math.min(left, viewportLeft + viewportEl.outerWidth() - width - this.margin);
            left = Math.max(left, viewportLeft + this.margin);
        }

        this.el.css({
            top: top - origin.top,
            left: left - origin.left
        });
    },


    // Triggers a callback. Calls a function in the option hash of the same name.
    // Arguments beyond the first `name` are forwarded on.
    // TODO: better code reuse for this. Repeat code
    trigger: function(name) {
        if (this.options[name]) {
            this.options[name].apply(this, Array.prototype.slice.call(arguments, 1));
        }
    }

});



/* A "coordinate map" converts pixel coordinates into an associated cell, which has an associated date
------------------------------------------------------------------------------------------------------------------------
Common interface:

    CoordMap.prototype = {
        build: function() {},
        getCell: function(x, y) {}
    };

*/

/* Coordinate map for a grid component
----------------------------------------------------------------------------------------------------------------------*/

var GridCoordMap = Class.extend({

    grid: null, // reference to the Grid
    rowCoords: null, // array of {top,bottom} objects
    colCoords: null, // array of {left,right} objects

    containerEl: null, // container element that all coordinates are constrained to. optionally assigned
    bounds: null,


    constructor: function(grid) {
        this.grid = grid;
    },


    // Queries the grid for the coordinates of all the cells
    build: function() {
        this.grid.build();
        this.rowCoords = this.grid.computeRowCoords();
        this.colCoords = this.grid.computeColCoords();
        this.computeBounds();
    },


    // Clears the coordinates data to free up memory
    clear: function() {
        this.grid.clear();
        this.rowCoords = null;
        this.colCoords = null;
    },


    // Given a coordinate of the document, gets the associated cell. If no cell is underneath, returns null
    getCell: function(x, y) {
        var rowCoords = this.rowCoords;
        var rowCnt = rowCoords.length;
        var colCoords = this.colCoords;
        var colCnt = colCoords.length;
        var hitRow = null;
        var hitCol = null;
        var i, coords;
        var cell;

        if (this.inBounds(x, y)) {

            for (i = 0; i < rowCnt; i++) {
                coords = rowCoords[i];
                if (y >= coords.top && y < coords.bottom) {
                    hitRow = i;
                    break;
                }
            }

            for (i = 0; i < colCnt; i++) {
                coords = colCoords[i];
                if (x >= coords.left && x < coords.right) {
                    hitCol = i;
                    break;
                }
            }

            if (hitRow !== null && hitCol !== null) {

                cell = this.grid.getCell(hitRow, hitCol); // expected to return a fresh object we can modify
                cell.grid = this.grid; // for CellDragListener's isCellsEqual. dragging between grids

                // make the coordinates available on the cell object
                $.extend(cell, rowCoords[hitRow], colCoords[hitCol]);

                return cell;
            }
        }

        return null;
    },


    // If there is a containerEl, compute the bounds into min/max values
    computeBounds: function() {
        this.bounds = this.containerEl ?
            getClientRect(this.containerEl) : // area within scrollbars
            null;
    },


    // Determines if the given coordinates are in bounds. If no `containerEl`, always true
    inBounds: function(x, y) {
        var bounds = this.bounds;

        if (bounds) {
            return x >= bounds.left && x < bounds.right && y >= bounds.top && y < bounds.bottom;
        }

        return true;
    }

});


/* Coordinate map that is a combination of multiple other coordinate maps
----------------------------------------------------------------------------------------------------------------------*/

var ComboCoordMap = Class.extend({

    coordMaps: null, // an array of CoordMaps


    constructor: function(coordMaps) {
        this.coordMaps = coordMaps;
    },


    // Builds all coordMaps
    build: function() {
        var coordMaps = this.coordMaps;
        var i;

        for (i = 0; i < coordMaps.length; i++) {
            coordMaps[i].build();
        }
    },


    // Queries all coordMaps for the cell underneath the given coordinates, returning the first result
    getCell: function(x, y) {
        var coordMaps = this.coordMaps;
        var cell = null;
        var i;

        for (i = 0; i < coordMaps.length && !cell; i++) {
            cell = coordMaps[i].getCell(x, y);
        }

        return cell;
    },


    // Clears all coordMaps
    clear: function() {
        var coordMaps = this.coordMaps;
        var i;

        for (i = 0; i < coordMaps.length; i++) {
            coordMaps[i].clear();
        }
    }

});



/* Tracks a drag's mouse movement, firing various handlers
----------------------------------------------------------------------------------------------------------------------*/

var DragListener = fc.DragListener = Class.extend({

    options: null,

    isListening: false,
    isDragging: false,

    // coordinates of the initial mousedown
    originX: null,
    originY: null,

    // handler attached to the document, bound to the DragListener's `this`
    mousemoveProxy: null,
    mouseupProxy: null,

    // for IE8 bug-fighting behavior, for now
    subjectEl: null, // the element being draged. optional
    subjectHref: null,

    scrollEl: null,
    scrollBounds: null, // { top, bottom, left, right }
    scrollTopVel: null, // pixels per second
    scrollLeftVel: null, // pixels per second
    scrollIntervalId: null, // ID of setTimeout for scrolling animation loop
    scrollHandlerProxy: null, // this-scoped function for handling when scrollEl is scrolled

    scrollSensitivity: 30, // pixels from edge for scrolling to start
    scrollSpeed: 200, // pixels per second, at maximum speed
    scrollIntervalMs: 50, // millisecond wait between scroll increment


    constructor: function(options) {
        options = options || {};
        this.options = options;
        this.subjectEl = options.subjectEl;
    },


    // Call this when the user does a mousedown. Will probably lead to startListening
    mousedown: function(ev) {
        if (isPrimaryMouseButton(ev)) {

            ev.preventDefault(); // prevents native selection in most browsers

            this.startListening(ev);

            // start the drag immediately if there is no minimum distance for a drag start
            if (!this.options.distance) {
                this.startDrag(ev);
            }
        }
    },


    // Call this to start tracking mouse movements
    startListening: function(ev) {
        var scrollParent;

        if (!this.isListening) {

            // grab scroll container and attach handler
            if (ev && this.options.scroll) {
                scrollParent = getScrollParent($(ev.target));
                if (!scrollParent.is(window) && !scrollParent.is(document)) {
                    this.scrollEl = scrollParent;

                    // scope to `this`, and use `debounce` to make sure rapid calls don't happen
                    this.scrollHandlerProxy = debounce(proxy(this, 'scrollHandler'), 100);
                    this.scrollEl.on('scroll', this.scrollHandlerProxy);
                }
            }

            $(document)
                .on('mousemove', this.mousemoveProxy = proxy(this, 'mousemove'))
                .on('mouseup', this.mouseupProxy = proxy(this, 'mouseup'))
                .on('selectstart', this.preventDefault); // prevents native selection in IE<=8

            if (ev) {
                this.originX = ev.pageX;
                this.originY = ev.pageY;
            }
            else {
                // if no starting information was given, origin will be the topleft corner of the screen.
                // if so, dx/dy in the future will be the absolute coordinates.
                this.originX = 0;
                this.originY = 0;
            }

            this.isListening = true;
            this.listenStart(ev);
        }
    },


    // Called when drag listening has started (but a real drag has not necessarily began)
    listenStart: function(ev) {
        this.trigger('listenStart', ev);
    },


    // Called when the user moves the mouse
    mousemove: function(ev) {
        var dx = ev.pageX - this.originX;
        var dy = ev.pageY - this.originY;
        var minDistance;
        var distanceSq; // current distance from the origin, squared

        if (!this.isDragging) { // if not already dragging...
            // then start the drag if the minimum distance criteria is met
            minDistance = this.options.distance || 1;
            distanceSq = dx * dx + dy * dy;
            if (distanceSq >= minDistance * minDistance) { // use pythagorean theorem
                this.startDrag(ev);
            }
        }

        if (this.isDragging) {
            this.drag(dx, dy, ev); // report a drag, even if this mousemove initiated the drag
        }
    },


    // Call this to initiate a legitimate drag.
    // This function is called internally from this class, but can also be called explicitly from outside
    startDrag: function(ev) {

        if (!this.isListening) { // startDrag must have manually initiated
            this.startListening();
        }

        if (!this.isDragging) {
            this.isDragging = true;
            this.dragStart(ev);
        }
    },


    // Called when the actual drag has started (went beyond minDistance)
    dragStart: function(ev) {
        var subjectEl = this.subjectEl;

        this.trigger('dragStart', ev);

        // remove a mousedown'd <a>'s href so it is not visited (IE8 bug)
        if ((this.subjectHref = subjectEl ? subjectEl.attr('href') : null)) {
            subjectEl.removeAttr('href');
        }
    },


    // Called while the mouse is being moved and when we know a legitimate drag is taking place
    drag: function(dx, dy, ev) {
        this.trigger('drag', dx, dy, ev);
        this.updateScroll(ev); // will possibly cause scrolling
    },


    // Called when the user does a mouseup
    mouseup: function(ev) {
        this.stopListening(ev);
    },


    // Called when the drag is over. Will not cause listening to stop however.
    // A concluding 'cellOut' event will NOT be triggered.
    stopDrag: function(ev) {
        if (this.isDragging) {
            this.stopScrolling();
            this.dragStop(ev);
            this.isDragging = false;
        }
    },


    // Called when dragging has been stopped
    dragStop: function(ev) {
        var _this = this;

        this.trigger('dragStop', ev);

        // restore a mousedown'd <a>'s href (for IE8 bug)
        setTimeout(function() { // must be outside of the click's execution
            if (_this.subjectHref) {
                _this.subjectEl.attr('href', _this.subjectHref);
            }
        }, 0);
    },


    // Call this to stop listening to the user's mouse events
    stopListening: function(ev) {
        this.stopDrag(ev); // if there's a current drag, kill it

        if (this.isListening) {

            // remove the scroll handler if there is a scrollEl
            if (this.scrollEl) {
                this.scrollEl.off('scroll', this.scrollHandlerProxy);
                this.scrollHandlerProxy = null;
            }

            $(document)
                .off('mousemove', this.mousemoveProxy)
                .off('mouseup', this.mouseupProxy)
                .off('selectstart', this.preventDefault);

            this.mousemoveProxy = null;
            this.mouseupProxy = null;

            this.isListening = false;
            this.listenStop(ev);
        }
    },


    // Called when drag listening has stopped
    listenStop: function(ev) {
        this.trigger('listenStop', ev);
    },


    // Triggers a callback. Calls a function in the option hash of the same name.
    // Arguments beyond the first `name` are forwarded on.
    trigger: function(name) {
        if (this.options[name]) {
            this.options[name].apply(this, Array.prototype.slice.call(arguments, 1));
        }
    },


    // Stops a given mouse event from doing it's native browser action. In our case, text selection.
    preventDefault: function(ev) {
        ev.preventDefault();
    },


    /* Scrolling
    ------------------------------------------------------------------------------------------------------------------*/


    // Computes and stores the bounding rectangle of scrollEl
    computeScrollBounds: function() {
        var el = this.scrollEl;

        this.scrollBounds = el ? getOuterRect(el) : null;
            // TODO: use getClientRect in future. but prevents auto scrolling when on top of scrollbars
    },


    // Called when the dragging is in progress and scrolling should be updated
    updateScroll: function(ev) {
        var sensitivity = this.scrollSensitivity;
        var bounds = this.scrollBounds;
        var topCloseness, bottomCloseness;
        var leftCloseness, rightCloseness;
        var topVel = 0;
        var leftVel = 0;

        if (bounds) { // only scroll if scrollEl exists

            // compute closeness to edges. valid range is from 0.0 - 1.0
            topCloseness = (sensitivity - (ev.pageY - bounds.top)) / sensitivity;
            bottomCloseness = (sensitivity - (bounds.bottom - ev.pageY)) / sensitivity;
            leftCloseness = (sensitivity - (ev.pageX - bounds.left)) / sensitivity;
            rightCloseness = (sensitivity - (bounds.right - ev.pageX)) / sensitivity;

            // translate vertical closeness into velocity.
            // mouse must be completely in bounds for velocity to happen.
            if (topCloseness >= 0 && topCloseness <= 1) {
                topVel = topCloseness * this.scrollSpeed * -1; // negative. for scrolling up
            }
            else if (bottomCloseness >= 0 && bottomCloseness <= 1) {
                topVel = bottomCloseness * this.scrollSpeed;
            }

            // translate horizontal closeness into velocity
            if (leftCloseness >= 0 && leftCloseness <= 1) {
                leftVel = leftCloseness * this.scrollSpeed * -1; // negative. for scrolling left
            }
            else if (rightCloseness >= 0 && rightCloseness <= 1) {
                leftVel = rightCloseness * this.scrollSpeed;
            }
        }

        this.setScrollVel(topVel, leftVel);
    },


    // Sets the speed-of-scrolling for the scrollEl
    setScrollVel: function(topVel, leftVel) {

        this.scrollTopVel = topVel;
        this.scrollLeftVel = leftVel;

        this.constrainScrollVel(); // massages into realistic values

        // if there is non-zero velocity, and an animation loop hasn't already started, then START
        if ((this.scrollTopVel || this.scrollLeftVel) && !this.scrollIntervalId) {
            this.scrollIntervalId = setInterval(
                proxy(this, 'scrollIntervalFunc'), // scope to `this`
                this.scrollIntervalMs
            );
        }
    },


    // Forces scrollTopVel and scrollLeftVel to be zero if scrolling has already gone all the way
    constrainScrollVel: function() {
        var el = this.scrollEl;

        if (this.scrollTopVel < 0) { // scrolling up?
            if (el.scrollTop() <= 0) { // already scrolled all the way up?
                this.scrollTopVel = 0;
            }
        }
        else if (this.scrollTopVel > 0) { // scrolling down?
            if (el.scrollTop() + el[0].clientHeight >= el[0].scrollHeight) { // already scrolled all the way down?
                this.scrollTopVel = 0;
            }
        }

        if (this.scrollLeftVel < 0) { // scrolling left?
            if (el.scrollLeft() <= 0) { // already scrolled all the left?
                this.scrollLeftVel = 0;
            }
        }
        else if (this.scrollLeftVel > 0) { // scrolling right?
            if (el.scrollLeft() + el[0].clientWidth >= el[0].scrollWidth) { // already scrolled all the way right?
                this.scrollLeftVel = 0;
            }
        }
    },


    // This function gets called during every iteration of the scrolling animation loop
    scrollIntervalFunc: function() {
        var el = this.scrollEl;
        var frac = this.scrollIntervalMs / 1000; // considering animation frequency, what the vel should be mult'd by

        // change the value of scrollEl's scroll
        if (this.scrollTopVel) {
            el.scrollTop(el.scrollTop() + this.scrollTopVel * frac);
        }
        if (this.scrollLeftVel) {
            el.scrollLeft(el.scrollLeft() + this.scrollLeftVel * frac);
        }

        this.constrainScrollVel(); // since the scroll values changed, recompute the velocities

        // if scrolled all the way, which causes the vels to be zero, stop the animation loop
        if (!this.scrollTopVel && !this.scrollLeftVel) {
            this.stopScrolling();
        }
    },


    // Kills any existing scrolling animation loop
    stopScrolling: function() {
        if (this.scrollIntervalId) {
            clearInterval(this.scrollIntervalId);
            this.scrollIntervalId = null;

            // when all done with scrolling, recompute positions since they probably changed
            this.scrollStop();
        }
    },


    // Get called when the scrollEl is scrolled (NOTE: this is delayed via debounce)
    scrollHandler: function() {
        // recompute all coordinates, but *only* if this is *not* part of our scrolling animation
        if (!this.scrollIntervalId) {
            this.scrollStop();
        }
    },


    // Called when scrolling has stopped, whether through auto scroll, or the user scrolling
    scrollStop: function() {
    }

});



/* Tracks mouse movements over a CoordMap and raises events about which cell the mouse is over.
------------------------------------------------------------------------------------------------------------------------
options:
- subjectEl
- subjectCenter
*/

var CellDragListener = DragListener.extend({

    coordMap: null, // converts coordinates to date cells
    origCell: null, // the cell the mouse was over when listening started
    cell: null, // the cell the mouse is over
    coordAdjust: null, // delta that will be added to the mouse coordinates when computing collisions


    constructor: function(coordMap, options) {
        DragListener.prototype.constructor.call(this, options); // call the super-constructor

        this.coordMap = coordMap;
    },


    // Called when drag listening starts (but a real drag has not necessarily began).
    // ev might be undefined if dragging was started manually.
    listenStart: function(ev) {
        var subjectEl = this.subjectEl;
        var subjectRect;
        var origPoint;
        var point;

        DragListener.prototype.listenStart.apply(this, arguments); // call the super-method

        this.computeCoords();

        if (ev) {
            origPoint = { left: ev.pageX, top: ev.pageY };
            point = origPoint;

            // constrain the point to bounds of the element being dragged
            if (subjectEl) {
                subjectRect = getOuterRect(subjectEl); // used for centering as well
                point = constrainPoint(point, subjectRect);
            }

            this.origCell = this.getCell(point.left, point.top);

            // treat the center of the subject as the collision point?
            if (subjectEl && this.options.subjectCenter) {

                // only consider the area the subject overlaps the cell. best for large subjects
                if (this.origCell) {
                    subjectRect = intersectRects(this.origCell, subjectRect) ||
                        subjectRect; // in case there is no intersection
                }

                point = getRectCenter(subjectRect);
            }

            this.coordAdjust = diffPoints(point, origPoint); // point - origPoint
        }
        else {
            this.origCell = null;
            this.coordAdjust = null;
        }
    },


    // Recomputes the drag-critical positions of elements
    computeCoords: function() {
        this.coordMap.build();
        this.computeScrollBounds();
    },


    // Called when the actual drag has started
    dragStart: function(ev) {
        var cell;

        DragListener.prototype.dragStart.apply(this, arguments); // call the super-method

        cell = this.getCell(ev.pageX, ev.pageY); // might be different from this.origCell if the min-distance is large

        // report the initial cell the mouse is over
        // especially important if no min-distance and drag starts immediately
        if (cell) {
            this.cellOver(cell);
        }
    },


    // Called when the drag moves
    drag: function(dx, dy, ev) {
        var cell;

        DragListener.prototype.drag.apply(this, arguments); // call the super-method

        cell = this.getCell(ev.pageX, ev.pageY);

        if (!isCellsEqual(cell, this.cell)) { // a different cell than before?
            if (this.cell) {
                this.cellOut();
            }
            if (cell) {
                this.cellOver(cell);
            }
        }
    },


    // Called when dragging has been stopped
    dragStop: function() {
        this.cellDone();
        DragListener.prototype.dragStop.apply(this, arguments); // call the super-method
    },


    // Called when a the mouse has just moved over a new cell
    cellOver: function(cell) {
        this.cell = cell;
        this.trigger('cellOver', cell, isCellsEqual(cell, this.origCell), this.origCell);
    },


    // Called when the mouse has just moved out of a cell
    cellOut: function() {
        if (this.cell) {
            this.trigger('cellOut', this.cell);
            this.cellDone();
            this.cell = null;
        }
    },


    // Called after a cellOut. Also called before a dragStop
    cellDone: function() {
        if (this.cell) {
            this.trigger('cellDone', this.cell);
        }
    },


    // Called when drag listening has stopped
    listenStop: function() {
        DragListener.prototype.listenStop.apply(this, arguments); // call the super-method

        this.origCell = this.cell = null;
        this.coordMap.clear();
    },


    // Called when scrolling has stopped, whether through auto scroll, or the user scrolling
    scrollStop: function() {
        DragListener.prototype.scrollStop.apply(this, arguments); // call the super-method

        this.computeCoords(); // cells' absolute positions will be in new places. recompute
    },


    // Gets the cell underneath the coordinates for the given mouse event
    getCell: function(left, top) {

        if (this.coordAdjust) {
            left += this.coordAdjust.left;
            top += this.coordAdjust.top;
        }

        return this.coordMap.getCell(left, top);
    }

});


// Returns `true` if the cells are identically equal. `false` otherwise.
// They must have the same row, col, and be from the same grid.
// Two null values will be considered equal, as two "out of the grid" states are the same.
function isCellsEqual(cell1, cell2) {

    if (!cell1 && !cell2) {
        return true;
    }

    if (cell1 && cell2) {
        return cell1.grid === cell2.grid &&
            cell1.row === cell2.row &&
            cell1.col === cell2.col;
    }

    return false;
}



/* Creates a clone of an element and lets it track the mouse as it moves
----------------------------------------------------------------------------------------------------------------------*/

var MouseFollower = Class.extend({

    options: null,

    sourceEl: null, // the element that will be cloned and made to look like it is dragging
    el: null, // the clone of `sourceEl` that will track the mouse
    parentEl: null, // the element that `el` (the clone) will be attached to

    // the initial position of el, relative to the offset parent. made to match the initial offset of sourceEl
    top0: null,
    left0: null,

    // the initial position of the mouse
    mouseY0: null,
    mouseX0: null,

    // the number of pixels the mouse has moved from its initial position
    topDelta: null,
    leftDelta: null,

    mousemoveProxy: null, // document mousemove handler, bound to the MouseFollower's `this`

    isFollowing: false,
    isHidden: false,
    isAnimating: false, // doing the revert animation?

    constructor: function(sourceEl, options) {
        this.options = options = options || {};
        this.sourceEl = sourceEl;
        this.parentEl = options.parentEl ? $(options.parentEl) : sourceEl.parent(); // default to sourceEl's parent
    },


    // Causes the element to start following the mouse
    start: function(ev) {
        if (!this.isFollowing) {
            this.isFollowing = true;

            this.mouseY0 = ev.pageY;
            this.mouseX0 = ev.pageX;
            this.topDelta = 0;
            this.leftDelta = 0;

            if (!this.isHidden) {
                this.updatePosition();
            }

            $(document).on('mousemove', this.mousemoveProxy = proxy(this, 'mousemove'));
        }
    },


    // Causes the element to stop following the mouse. If shouldRevert is true, will animate back to original position.
    // `callback` gets invoked when the animation is complete. If no animation, it is invoked immediately.
    stop: function(shouldRevert, callback) {
        var _this = this;
        var revertDuration = this.options.revertDuration;

        function complete() {
            this.isAnimating = false;
            _this.removeElement();

            this.top0 = this.left0 = null; // reset state for future updatePosition calls

            if (callback) {
                callback();
            }
        }

        if (this.isFollowing && !this.isAnimating) { // disallow more than one stop animation at a time
            this.isFollowing = false;

            $(document).off('mousemove', this.mousemoveProxy);

            if (shouldRevert && revertDuration && !this.isHidden) { // do a revert animation?
                this.isAnimating = true;
                this.el.animate({
                    top: this.top0,
                    left: this.left0
                }, {
                    duration: revertDuration,
                    complete: complete
                });
            }
            else {
                complete();
            }
        }
    },


    // Gets the tracking element. Create it if necessary
    getEl: function() {
        var el = this.el;

        if (!el) {
            this.sourceEl.width(); // hack to force IE8 to compute correct bounding box
            el = this.el = this.sourceEl.clone()
                .css({
                    position: 'absolute',
                    visibility: '', // in case original element was hidden (commonly through hideEvents())
                    display: this.isHidden ? 'none' : '', // for when initially hidden
                    margin: 0,
                    right: 'auto', // erase and set width instead
                    bottom: 'auto', // erase and set height instead
                    width: this.sourceEl.width(), // explicit height in case there was a 'right' value
                    height: this.sourceEl.height(), // explicit width in case there was a 'bottom' value
                    opacity: this.options.opacity || '',
                    zIndex: this.options.zIndex
                })
                .appendTo(this.parentEl);
        }

        return el;
    },


    // Removes the tracking element if it has already been created
    removeElement: function() {
        if (this.el) {
            this.el.remove();
            this.el = null;
        }
    },


    // Update the CSS position of the tracking element
    updatePosition: function() {
        var sourceOffset;
        var origin;

        this.getEl(); // ensure this.el

        // make sure origin info was computed
        if (this.top0 === null) {
            this.sourceEl.width(); // hack to force IE8 to compute correct bounding box
            sourceOffset = this.sourceEl.offset();
            origin = this.el.offsetParent().offset();
            this.top0 = sourceOffset.top - origin.top;
            this.left0 = sourceOffset.left - origin.left;
        }

        this.el.css({
            top: this.top0 + this.topDelta,
            left: this.left0 + this.leftDelta
        });
    },


    // Gets called when the user moves the mouse
    mousemove: function(ev) {
        this.topDelta = ev.pageY - this.mouseY0;
        this.leftDelta = ev.pageX - this.mouseX0;

        if (!this.isHidden) {
            this.updatePosition();
        }
    },


    // Temporarily makes the tracking element invisible. Can be called before following starts
    hide: function() {
        if (!this.isHidden) {
            this.isHidden = true;
            if (this.el) {
                this.el.hide();
            }
        }
    },


    // Show the tracking element after it has been temporarily hidden
    show: function() {
        if (this.isHidden) {
            this.isHidden = false;
            this.updatePosition();
            this.getEl().show();
        }
    }

});



/* A utility class for rendering <tr> rows.
----------------------------------------------------------------------------------------------------------------------*/
// It leverages methods of the subclass and the View to determine custom rendering behavior for each row "type"
// (such as highlight rows, day rows, helper rows, etc).

var RowRenderer = Class.extend({

    view: null, // a View object
    isRTL: null, // shortcut to the view's isRTL option
    cellHtml: '<td/>', // plain default HTML used for a cell when no other is available


    constructor: function(view) {
        this.view = view;
        this.isRTL = view.opt('isRTL');
    },


    // Renders the HTML for a row, leveraging custom cell-HTML-renderers based on the `rowType`.
    // Also applies the "intro" and "outro" cells, which are specified by the subclass and views.
    // `row` is an optional row number.
    rowHtml: function(rowType, row) {
        var renderCell = this.getHtmlRenderer('cell', rowType);
        var rowCellHtml = '';
        var col;
        var cell;

        row = row || 0;

        for (col = 0; col < this.colCnt; col++) {
            cell = this.getCell(row, col);
            rowCellHtml += renderCell(cell);
        }

        rowCellHtml = this.bookendCells(rowCellHtml, rowType, row); // apply intro and outro

        return '<tr>' + rowCellHtml + '</tr>';
    },


    // Applies the "intro" and "outro" HTML to the given cells.
    // Intro means the leftmost cell when the calendar is LTR and the rightmost cell when RTL. Vice-versa for outro.
    // `cells` can be an HTML string of <td>'s or a jQuery <tr> element
    // `row` is an optional row number.
    bookendCells: function(cells, rowType, row) {
        var intro = this.getHtmlRenderer('intro', rowType)(row || 0);
        var outro = this.getHtmlRenderer('outro', rowType)(row || 0);
        var prependHtml = this.isRTL ? outro : intro;
        var appendHtml = this.isRTL ? intro : outro;

        if (typeof cells === 'string') {
            return prependHtml + cells + appendHtml;
        }
        else { // a jQuery <tr> element
            return cells.prepend(prependHtml).append(appendHtml);
        }
    },


    // Returns an HTML-rendering function given a specific `rendererName` (like cell, intro, or outro) and a specific
    // `rowType` (like day, eventSkeleton, helperSkeleton), which is optional.
    // If a renderer for the specific rowType doesn't exist, it will fall back to a generic renderer.
    // We will query the View object first for any custom rendering functions, then the methods of the subclass.
    getHtmlRenderer: function(rendererName, rowType) {
        var view = this.view;
        var generalName; // like "cellHtml"
        var specificName; // like "dayCellHtml". based on rowType
        var provider; // either the View or the RowRenderer subclass, whichever provided the method
        var renderer;

        generalName = rendererName + 'Html';
        if (rowType) {
            specificName = rowType + capitaliseFirstLetter(rendererName) + 'Html';
        }

        if (specificName && (renderer = view[specificName])) {
            provider = view;
        }
        else if (specificName && (renderer = this[specificName])) {
            provider = this;
        }
        else if ((renderer = view[generalName])) {
            provider = view;
        }
        else if ((renderer = this[generalName])) {
            provider = this;
        }

        if (typeof renderer === 'function') {
            return function() {
                return renderer.apply(provider, arguments) || ''; // use correct `this` and always return a string
            };
        }

        // the rendered can be a plain string as well. if not specified, always an empty string.
        return function() {
            return renderer || '';
        };
    }

});



/* An abstract class comprised of a "grid" of cells that each represent a specific datetime
----------------------------------------------------------------------------------------------------------------------*/

var Grid = fc.Grid = RowRenderer.extend({

    start: null, // the date of the first cell
    end: null, // the date after the last cell

    rowCnt: 0, // number of rows
    colCnt: 0, // number of cols

    el: null, // the containing element
    coordMap: null, // a GridCoordMap that converts pixel values to datetimes
    elsByFill: null, // a hash of jQuery element sets used for rendering each fill. Keyed by fill name.

    externalDragStartProxy: null, // binds the Grid's scope to externalDragStart (in DayGrid.events)

    // derived from options
    colHeadFormat: null, // TODO: move to another class. not applicable to all Grids
    eventTimeFormat: null,
    displayEventTime: null,
    displayEventEnd: null,

    // if all cells are the same length of time, the duration they all share. optional.
    // when defined, allows the computeCellRange shortcut, as well as improved resizing behavior.
    cellDuration: null,

    // if defined, holds the unit identified (ex: "year" or "month") that determines the level of granularity
    // of the date cells. if not defined, assumes to be day and time granularity.
    largeUnit: null,


    constructor: function() {
        RowRenderer.apply(this, arguments); // call the super-constructor

        this.coordMap = new GridCoordMap(this);
        this.elsByFill = {};
        this.externalDragStartProxy = proxy(this, 'externalDragStart');
    },


    /* Options
    ------------------------------------------------------------------------------------------------------------------*/


    // Generates the format string used for the text in column headers, if not explicitly defined by 'columnFormat'
    // TODO: move to another class. not applicable to all Grids
    computeColHeadFormat: function() {
        // subclasses must implement if they want to use headHtml()
    },


    // Generates the format string used for event time text, if not explicitly defined by 'timeFormat'
    computeEventTimeFormat: function() {
        return this.view.opt('smallTimeFormat');
    },


    // Determines whether events should have their end times displayed, if not explicitly defined by 'displayEventTime'.
    // Only applies to non-all-day events.
    computeDisplayEventTime: function() {
        return true;
    },


    // Determines whether events should have their end times displayed, if not explicitly defined by 'displayEventEnd'
    computeDisplayEventEnd: function() {
        return true;
    },


    /* Dates
    ------------------------------------------------------------------------------------------------------------------*/


    // Tells the grid about what period of time to display.
    // Any date-related cell system internal data should be generated.
    setRange: function(range) {
        this.start = range.start.clone();
        this.end = range.end.clone();

        this.rangeUpdated();
        this.processRangeOptions();
    },


    // Called when internal variables that rely on the range should be updated
    rangeUpdated: function() {
    },


    // Updates values that rely on options and also relate to range
    processRangeOptions: function() {
        var view = this.view;
        var displayEventTime;
        var displayEventEnd;

        // Populate option-derived settings. Look for override first, then compute if necessary.
        this.colHeadFormat = view.opt('columnFormat') || this.computeColHeadFormat();

        this.eventTimeFormat =
            view.opt('eventTimeFormat') ||
            view.opt('timeFormat') || // deprecated
            this.computeEventTimeFormat();

        displayEventTime = view.opt('displayEventTime');
        if (displayEventTime == null) {
            displayEventTime = this.computeDisplayEventTime(); // might be based off of range
        }

        displayEventEnd = view.opt('displayEventEnd');
        if (displayEventEnd == null) {
            displayEventEnd = this.computeDisplayEventEnd(); // might be based off of range
        }

        this.displayEventTime = displayEventTime;
        this.displayEventEnd = displayEventEnd;
    },


    // Called before the grid's coordinates will need to be queried for cells.
    // Any non-date-related cell system internal data should be built.
    build: function() {
    },


    // Called after the grid's coordinates are done being relied upon.
    // Any non-date-related cell system internal data should be cleared.
    clear: function() {
    },


    // Converts a range with an inclusive `start` and an exclusive `end` into an array of segment objects
    rangeToSegs: function(range) {
        // subclasses must implement
    },


    // Diffs the two dates, returning a duration, based on granularity of the grid
    diffDates: function(a, b) {
        if (this.largeUnit) {
            return diffByUnit(a, b, this.largeUnit);
        }
        else {
            return diffDayTime(a, b);
        }
    },


    /* Cells
    ------------------------------------------------------------------------------------------------------------------*/
    // NOTE: columns are ordered left-to-right


    // Gets an object containing row/col number, misc data, and range information about the cell.
    // Accepts row/col values, an object with row/col properties, or a single-number offset from the first cell.
    getCell: function(row, col) {
        var cell;

        if (col == null) {
            if (typeof row === 'number') { // a single-number offset
                col = row % this.colCnt;
                row = Math.floor(row / this.colCnt);
            }
            else { // an object with row/col properties
                col = row.col;
                row = row.row;
            }
        }

        cell = { row: row, col: col };

        $.extend(cell, this.getRowData(row), this.getColData(col));
        $.extend(cell, this.computeCellRange(cell));

        return cell;
    },


    // Given a cell object with index and misc data, generates a range object
    // If the grid is leveraging cellDuration, this doesn't need to be defined. Only computeCellDate does.
    // If being overridden, should return a range with reference-free date copies.
    computeCellRange: function(cell) {
        var date = this.computeCellDate(cell);

        return {
            start: date,
            end: date.clone().add(this.cellDuration)
        };
    },


    // Given a cell, returns its start date. Should return a reference-free date copy.
    computeCellDate: function(cell) {
        // subclasses can implement
    },


    // Retrieves misc data about the given row
    getRowData: function(row) {
        return {};
    },


    // Retrieves misc data baout the given column
    getColData: function(col) {
        return {};
    },


    // Retrieves the element representing the given row
    getRowEl: function(row) {
        // subclasses should implement if leveraging the default getCellDayEl() or computeRowCoords()
    },


    // Retrieves the element representing the given column
    getColEl: function(col) {
        // subclasses should implement if leveraging the default getCellDayEl() or computeColCoords()
    },


    // Given a cell object, returns the element that represents the cell's whole-day
    getCellDayEl: function(cell) {
        return this.getColEl(cell.col) || this.getRowEl(cell.row);
    },


    /* Cell Coordinates
    ------------------------------------------------------------------------------------------------------------------*/


    // Computes the top/bottom coordinates of all rows.
    // By default, queries the dimensions of the element provided by getRowEl().
    computeRowCoords: function() {
        var items = [];
        var i, el;
        var top;

        for (i = 0; i < this.rowCnt; i++) {
            el = this.getRowEl(i);
            top = el.offset().top;
            items.push({
                top: top,
                bottom: top + el.outerHeight()
            });
        }

        return items;
    },


    // Computes the left/right coordinates of all rows.
    // By default, queries the dimensions of the element provided by getColEl(). Columns can be LTR or RTL.
    computeColCoords: function() {
        var items = [];
        var i, el;
        var left;

        for (i = 0; i < this.colCnt; i++) {
            el = this.getColEl(i);
            left = el.offset().left;
            items.push({
                left: left,
                right: left + el.outerWidth()
            });
        }

        return items;
    },


    /* Rendering
    ------------------------------------------------------------------------------------------------------------------*/


    // Sets the container element that the grid should render inside of.
    // Does other DOM-related initializations.
    setElement: function(el) {
        var _this = this;

        this.el = el;

        // attach a handler to the grid's root element.
        // jQuery will take care of unregistering them when removeElement gets called.
        el.on('mousedown', function(ev) {
            if (
                !$(ev.target).is('.fc-event-container *, .fc-more') && // not an an event element, or "more.." link
                !$(ev.target).closest('.fc-popover').length // not on a popover (like the "more.." events one)
            ) {
                _this.dayMousedown(ev);
            }
        });

        // attach event-element-related handlers. in Grid.events
        // same garbage collection note as above.
        this.bindSegHandlers();

        this.bindGlobalHandlers();
    },


    // Removes the grid's container element from the DOM. Undoes any other DOM-related attachments.
    // DOES NOT remove any content beforehand (doesn't clear events or call unrenderDates), unlike View
    removeElement: function() {
        this.unbindGlobalHandlers();

        this.el.remove();

        // NOTE: we don't null-out this.el for the same reasons we don't do it within View::removeElement
    },


    // Renders the basic structure of grid view before any content is rendered
    renderSkeleton: function() {
        // subclasses should implement
    },


    // Renders the grid's date-related content (like cells that represent days/times).
    // Assumes setRange has already been called and the skeleton has already been rendered.
    renderDates: function() {
        // subclasses should implement
    },


    // Unrenders the grid's date-related content
    unrenderDates: function() {
        // subclasses should implement
    },


    /* Handlers
    ------------------------------------------------------------------------------------------------------------------*/


    // Binds DOM handlers to elements that reside outside the grid, such as the document
    bindGlobalHandlers: function() {
        $(document).on('dragstart sortstart', this.externalDragStartProxy); // jqui
    },


    // Unbinds DOM handlers from elements that reside outside the grid
    unbindGlobalHandlers: function() {
        $(document).off('dragstart sortstart', this.externalDragStartProxy); // jqui
    },


    // Process a mousedown on an element that represents a day. For day clicking and selecting.
    dayMousedown: function(ev) {
        var _this = this;
        var view = this.view;
        var isSelectable = view.opt('selectable');
        var dayClickCell; // null if invalid dayClick
        var selectionRange; // null if invalid selection

        // this listener tracks a mousedown on a day element, and a subsequent drag.
        // if the drag ends on the same day, it is a 'dayClick'.
        // if 'selectable' is enabled, this listener also detects selections.
        var dragListener = new CellDragListener(this.coordMap, {
            //distance: 5, // needs more work if we want dayClick to fire correctly
            scroll: view.opt('dragScroll'),
            dragStart: function() {
                view.unselect(); // since we could be rendering a new selection, we want to clear any old one
            },
            cellOver: function(cell, isOrig, origCell) {
                if (origCell) { // click needs to have started on a cell
                    dayClickCell = isOrig ? cell : null; // single-cell selection is a day click
                    if (isSelectable) {
                        selectionRange = _this.computeSelection(origCell, cell);
                        if (selectionRange) {
                            _this.renderSelection(selectionRange);
                        }
                        else {
                            disableCursor();
                        }
                    }
                }
            },
            cellOut: function(cell) {
                dayClickCell = null;
                selectionRange = null;
                _this.unrenderSelection();
                enableCursor();
            },
            listenStop: function(ev) {
                if (dayClickCell) {
                    view.triggerDayClick(dayClickCell, _this.getCellDayEl(dayClickCell), ev);
                }
                if (selectionRange) {
                    // the selection will already have been rendered. just report it
                    view.reportSelection(selectionRange, ev);
                }
                enableCursor();
            }
        });

        dragListener.mousedown(ev); // start listening, which will eventually initiate a dragStart
    },


    /* Event Helper
    ------------------------------------------------------------------------------------------------------------------*/
    // TODO: should probably move this to Grid.events, like we did event dragging / resizing


    // Renders a mock event over the given range
    renderRangeHelper: function(range, sourceSeg) {
        var fakeEvent = this.fabricateHelperEvent(range, sourceSeg);

        this.renderHelper(fakeEvent, sourceSeg); // do the actual rendering
    },


    // Builds a fake event given a date range it should cover, and a segment is should be inspired from.
    // The range's end can be null, in which case the mock event that is rendered will have a null end time.
    // `sourceSeg` is the internal segment object involved in the drag. If null, something external is dragging.
    fabricateHelperEvent: function(range, sourceSeg) {
        var fakeEvent = sourceSeg ? createObject(sourceSeg.event) : {}; // mask the original event object if possible

        fakeEvent.start = range.start.clone();
        fakeEvent.end = range.end ? range.end.clone() : null;
        fakeEvent.allDay = null; // force it to be freshly computed by normalizeEventRange
        this.view.calendar.normalizeEventRange(fakeEvent);

        // this extra className will be useful for differentiating real events from mock events in CSS
        fakeEvent.className = (fakeEvent.className || []).concat('fc-helper');

        // if something external is being dragged in, don't render a resizer
        if (!sourceSeg) {
            fakeEvent.editable = false;
        }

        return fakeEvent;
    },


    // Renders a mock event
    renderHelper: function(event, sourceSeg) {
        // subclasses must implement
    },


    // Unrenders a mock event
    unrenderHelper: function() {
        // subclasses must implement
    },


    /* Selection
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of a selection. Will highlight by default but can be overridden by subclasses.
    renderSelection: function(range) {
        this.renderHighlight(this.selectionRangeToSegs(range));
    },


    // Unrenders any visual indications of a selection. Will unrender a highlight by default.
    unrenderSelection: function() {
        this.unrenderHighlight();
    },


    // Given the first and last cells of a selection, returns a range object.
    // Will return something falsy if the selection is invalid (when outside of selectionConstraint for example).
    // Subclasses can override and provide additional data in the range object. Will be passed to renderSelection().
    computeSelection: function(firstCell, lastCell) {
        var dates = [
            firstCell.start,
            firstCell.end,
            lastCell.start,
            lastCell.end
        ];
        var range;

        dates.sort(compareNumbers); // sorts chronologically. works with Moments

        range = {
            start: dates[0].clone(),
            end: dates[3].clone()
        };

        if (!this.view.calendar.isSelectionRangeAllowed(range)) {
            return null;
        }

        return range;
    },


    selectionRangeToSegs: function(range) {
        return this.rangeToSegs(range);
    },


    /* Highlight
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders an emphasis on the given date range. Given an array of segments.
    renderHighlight: function(segs) {
        this.renderFill('highlight', segs);
    },


    // Unrenders the emphasis on a date range
    unrenderHighlight: function() {
        this.unrenderFill('highlight');
    },


    // Generates an array of classNames for rendering the highlight. Used by the fill system.
    highlightSegClasses: function() {
        return [ 'fc-highlight' ];
    },


    /* Fill System (highlight, background events, business hours)
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a set of rectangles over the given segments of time.
    // MUST RETURN a subset of segs, the segs that were actually rendered.
    // Responsible for populating this.elsByFill. TODO: better API for expressing this requirement
    renderFill: function(type, segs) {
        // subclasses must implement
    },


    // Unrenders a specific type of fill that is currently rendered on the grid
    unrenderFill: function(type) {
        var el = this.elsByFill[type];

        if (el) {
            el.remove();
            delete this.elsByFill[type];
        }
    },


    // Renders and assigns an `el` property for each fill segment. Generic enough to work with different types.
    // Only returns segments that successfully rendered.
    // To be harnessed by renderFill (implemented by subclasses).
    // Analagous to renderFgSegEls.
    renderFillSegEls: function(type, segs) {
        var _this = this;
        var segElMethod = this[type + 'SegEl'];
        var html = '';
        var renderedSegs = [];
        var i;

        if (segs.length) {

            // build a large concatenation of segment HTML
            for (i = 0; i < segs.length; i++) {
                html += this.fillSegHtml(type, segs[i]);
            }

            // Grab individual elements from the combined HTML string. Use each as the default rendering.
            // Then, compute the 'el' for each segment.
            $(html).each(function(i, node) {
                var seg = segs[i];
                var el = $(node);

                // allow custom filter methods per-type
                if (segElMethod) {
                    el = segElMethod.call(_this, seg, el);
                }

                if (el) { // custom filters did not cancel the render
                    el = $(el); // allow custom filter to return raw DOM node

                    // correct element type? (would be bad if a non-TD were inserted into a table for example)
                    if (el.is(_this.fillSegTag)) {
                        seg.el = el;
                        renderedSegs.push(seg);
                    }
                }
            });
        }

        return renderedSegs;
    },


    fillSegTag: 'div', // subclasses can override


    // Builds the HTML needed for one fill segment. Generic enought o work with different types.
    fillSegHtml: function(type, seg) {

        // custom hooks per-type
        var classesMethod = this[type + 'SegClasses'];
        var cssMethod = this[type + 'SegCss'];

        var classes = classesMethod ? classesMethod.call(this, seg) : [];
        var css = cssToStr(cssMethod ? cssMethod.call(this, seg) : {});

        return '<' + this.fillSegTag +
            (classes.length ? ' class="' + classes.join(' ') + '"' : '') +
            (css ? ' style="' + css + '"' : '') +
            ' />';
    },


    /* Generic rendering utilities for subclasses
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a day-of-week header row.
    // TODO: move to another class. not applicable to all Grids
    headHtml: function() {
        return '' +
            '<div class="fc-row ' + this.view.widgetHeaderClass + '">' +
                '<table>' +
                    '<thead>' +
                        this.rowHtml('head') + // leverages RowRenderer
                    '</thead>' +
                '</table>' +
            '</div>';
    },


    // Used by the `headHtml` method, via RowRenderer, for rendering the HTML of a day-of-week header cell
    // TODO: move to another class. not applicable to all Grids
    headCellHtml: function(cell) {
        var view = this.view;
        var date = cell.start;

        return '' +
            '<th class="fc-day-header ' + view.widgetHeaderClass + ' fc-' + dayIDs[date.day()] + '">' +
                htmlEscape(date.format(this.colHeadFormat)) +
            '</th>';
    },


    // Renders the HTML for a single-day background cell
    bgCellHtml: function(cell) {
        var view = this.view;
        var date = cell.start;
        var classes = this.getDayClasses(date);

        classes.unshift('fc-day', view.widgetContentClass);

        return '<td class="' + classes.join(' ') + '"' +
            ' data-date="' + date.format('YYYY-MM-DD') + '"' + // if date has a time, won't format it
            '></td>';
    },


    // Computes HTML classNames for a single-day cell
    getDayClasses: function(date) {
        var view = this.view;
        var today = view.calendar.getNow().stripTime();
        var classes = [ 'fc-' + dayIDs[date.day()] ];

        if (
            view.intervalDuration.as('months') == 1 &&
            date.month() != view.intervalStart.month()
        ) {
            classes.push('fc-other-month');
        }

        if (date.isSame(today, 'day')) {
            classes.push(
                'fc-today',
                view.highlightStateClass
            );
        }
        else if (date < today) {
            classes.push('fc-past');
        }
        else {
            classes.push('fc-future');
        }

        return classes;
    }

});



/* Event-rendering and event-interaction methods for the abstract Grid class
----------------------------------------------------------------------------------------------------------------------*/

Grid.mixin({

    mousedOverSeg: null, // the segment object the user's mouse is over. null if over nothing
    isDraggingSeg: false, // is a segment being dragged? boolean
    isResizingSeg: false, // is a segment being resized? boolean
    isDraggingExternal: false, // jqui-dragging an external element? boolean
    segs: null, // the event segments currently rendered in the grid


    // Renders the given events onto the grid
    renderEvents: function(events) {
        var segs = this.eventsToSegs(events);
        var bgSegs = [];
        var fgSegs = [];
        var i, seg;

        for (i = 0; i < segs.length; i++) {
            seg = segs[i];

            if (isBgEvent(seg.event)) {
                bgSegs.push(seg);
            }
            else {
                fgSegs.push(seg);
            }
        }

        // Render each different type of segment.
        // Each function may return a subset of the segs, segs that were actually rendered.
        bgSegs = this.renderBgSegs(bgSegs) || bgSegs;
        fgSegs = this.renderFgSegs(fgSegs) || fgSegs;

        this.segs = bgSegs.concat(fgSegs);
    },


    // Unrenders all events currently rendered on the grid
    unrenderEvents: function() {
        this.triggerSegMouseout(); // trigger an eventMouseout if user's mouse is over an event

        this.unrenderFgSegs();
        this.unrenderBgSegs();

        this.segs = null;
    },


    // Retrieves all rendered segment objects currently rendered on the grid
    getEventSegs: function() {
        return this.segs || [];
    },


    /* Foreground Segment Rendering
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders foreground event segments onto the grid. May return a subset of segs that were rendered.
    renderFgSegs: function(segs) {
        // subclasses must implement
    },


    // Unrenders all currently rendered foreground segments
    unrenderFgSegs: function() {
        // subclasses must implement
    },


    // Renders and assigns an `el` property for each foreground event segment.
    // Only returns segments that successfully rendered.
    // A utility that subclasses may use.
    renderFgSegEls: function(segs, disableResizing) {
        var view = this.view;
        var html = '';
        var renderedSegs = [];
        var i;

        if (segs.length) { // don't build an empty html string

            // build a large concatenation of event segment HTML
            for (i = 0; i < segs.length; i++) {
                html += this.fgSegHtml(segs[i], disableResizing);
            }

            // Grab individual elements from the combined HTML string. Use each as the default rendering.
            // Then, compute the 'el' for each segment. An el might be null if the eventRender callback returned false.
            $(html).each(function(i, node) {
                var seg = segs[i];
                var el = view.resolveEventEl(seg.event, $(node));

                if (el) {
                    el.data('fc-seg', seg); // used by handlers
                    seg.el = el;
                    renderedSegs.push(seg);
                }
            });
        }

        return renderedSegs;
    },


    // Generates the HTML for the default rendering of a foreground event segment. Used by renderFgSegEls()
    fgSegHtml: function(seg, disableResizing) {
        // subclasses should implement
    },


    /* Background Segment Rendering
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders the given background event segments onto the grid.
    // Returns a subset of the segs that were actually rendered.
    renderBgSegs: function(segs) {
        return this.renderFill('bgEvent', segs);
    },


    // Unrenders all the currently rendered background event segments
    unrenderBgSegs: function() {
        this.unrenderFill('bgEvent');
    },


    // Renders a background event element, given the default rendering. Called by the fill system.
    bgEventSegEl: function(seg, el) {
        return this.view.resolveEventEl(seg.event, el); // will filter through eventRender
    },


    // Generates an array of classNames to be used for the default rendering of a background event.
    // Called by the fill system.
    bgEventSegClasses: function(seg) {
        var event = seg.event;
        var source = event.source || {};

        return [ 'fc-bgevent' ].concat(
            event.className,
            source.className || []
        );
    },


    // Generates a semicolon-separated CSS string to be used for the default rendering of a background event.
    // Called by the fill system.
    // TODO: consolidate with getEventSkinCss?
    bgEventSegCss: function(seg) {
        var view = this.view;
        var event = seg.event;
        var source = event.source || {};

        return {
            'background-color':
                event.backgroundColor ||
                event.color ||
                source.backgroundColor ||
                source.color ||
                view.opt('eventBackgroundColor') ||
                view.opt('eventColor')
        };
    },


    // Generates an array of classNames to be used for the rendering business hours overlay. Called by the fill system.
    businessHoursSegClasses: function(seg) {
        return [ 'fc-nonbusiness', 'fc-bgevent' ];
    },


    /* Handlers
    ------------------------------------------------------------------------------------------------------------------*/


    // Attaches event-element-related handlers to the container element and leverage bubbling
    bindSegHandlers: function() {
        var _this = this;
        var view = this.view;

        $.each(
            {
                mouseenter: function(seg, ev) {
                    _this.triggerSegMouseover(seg, ev);
                },
                mouseleave: function(seg, ev) {
                    _this.triggerSegMouseout(seg, ev);
                },
                click: function(seg, ev) {
                    return view.trigger('eventClick', this, seg.event, ev); // can return `false` to cancel
                },
                mousedown: function(seg, ev) {
                    if ($(ev.target).is('.fc-resizer') && view.isEventResizable(seg.event)) {
                        _this.segResizeMousedown(seg, ev, $(ev.target).is('.fc-start-resizer'));
                    }
                    else if (view.isEventDraggable(seg.event)) {
                        _this.segDragMousedown(seg, ev);
                    }
                }
            },
            function(name, func) {
                // attach the handler to the container element and only listen for real event elements via bubbling
                _this.el.on(name, '.fc-event-container > *', function(ev) {
                    var seg = $(this).data('fc-seg'); // grab segment data. put there by View::renderEvents

                    // only call the handlers if there is not a drag/resize in progress
                    if (seg && !_this.isDraggingSeg && !_this.isResizingSeg) {
                        return func.call(this, seg, ev); // `this` will be the event element
                    }
                });
            }
        );
    },


    // Updates internal state and triggers handlers for when an event element is moused over
    triggerSegMouseover: function(seg, ev) {
        if (!this.mousedOverSeg) {
            this.mousedOverSeg = seg;
            this.view.trigger('eventMouseover', seg.el[0], seg.event, ev);
        }
    },


    // Updates internal state and triggers handlers for when an event element is moused out.
    // Can be given no arguments, in which case it will mouseout the segment that was previously moused over.
    triggerSegMouseout: function(seg, ev) {
        ev = ev || {}; // if given no args, make a mock mouse event

        if (this.mousedOverSeg) {
            seg = seg || this.mousedOverSeg; // if given no args, use the currently moused-over segment
            this.mousedOverSeg = null;
            this.view.trigger('eventMouseout', seg.el[0], seg.event, ev);
        }
    },


    /* Event Dragging
    ------------------------------------------------------------------------------------------------------------------*/


    // Called when the user does a mousedown on an event, which might lead to dragging.
    // Generic enough to work with any type of Grid.
    segDragMousedown: function(seg, ev) {
        var _this = this;
        var view = this.view;
        var calendar = view.calendar;
        var el = seg.el;
        var event = seg.event;
        var dropLocation;

        // A clone of the original element that will move with the mouse
        var mouseFollower = new MouseFollower(seg.el, {
            parentEl: view.el,
            opacity: view.opt('dragOpacity'),
            revertDuration: view.opt('dragRevertDuration'),
            zIndex: 2 // one above the .fc-view
        });

        // Tracks mouse movement over the *view's* coordinate map. Allows dragging and dropping between subcomponents
        // of the view.
        var dragListener = new CellDragListener(view.coordMap, {
            distance: 5,
            scroll: view.opt('dragScroll'),
            subjectEl: el,
            subjectCenter: true,
            listenStart: function(ev) {
                mouseFollower.hide(); // don't show until we know this is a real drag
                mouseFollower.start(ev);
            },
            dragStart: function(ev) {
                _this.triggerSegMouseout(seg, ev); // ensure a mouseout on the manipulated event has been reported
                _this.segDragStart(seg, ev);
                view.hideEvent(event); // hide all event segments. our mouseFollower will take over
            },
            cellOver: function(cell, isOrig, origCell) {

                // starting cell could be forced (DayGrid.limit)
                if (seg.cell) {
                    origCell = seg.cell;
                }

                dropLocation = _this.computeEventDrop(origCell, cell, event);

                if (dropLocation && !calendar.isEventRangeAllowed(dropLocation, event)) {
                    disableCursor();
                    dropLocation = null;
                }

                // if a valid drop location, have the subclass render a visual indication
                if (dropLocation && view.renderDrag(dropLocation, seg)) {
                    mouseFollower.hide(); // if the subclass is already using a mock event "helper", hide our own
                }
                else {
                    mouseFollower.show(); // otherwise, have the helper follow the mouse (no snapping)
                }

                if (isOrig) {
                    dropLocation = null; // needs to have moved cells to be a valid drop
                }
            },
            cellOut: function() { // called before mouse moves to a different cell OR moved out of all cells
                view.unrenderDrag(); // unrender whatever was done in renderDrag
                mouseFollower.show(); // show in case we are moving out of all cells
                dropLocation = null;
            },
            cellDone: function() { // Called after a cellOut OR before a dragStop
                enableCursor();
            },
            dragStop: function(ev) {
                // do revert animation if hasn't changed. calls a callback when finished (whether animation or not)
                mouseFollower.stop(!dropLocation, function() {
                    view.unrenderDrag();
                    view.showEvent(event);
                    _this.segDragStop(seg, ev);

                    if (dropLocation) {
                        view.reportEventDrop(event, dropLocation, this.largeUnit, el, ev);
                    }
                });
            },
            listenStop: function() {
                mouseFollower.stop(); // put in listenStop in case there was a mousedown but the drag never started
            }
        });

        dragListener.mousedown(ev); // start listening, which will eventually lead to a dragStart
    },


    // Called before event segment dragging starts
    segDragStart: function(seg, ev) {
        this.isDraggingSeg = true;
        this.view.trigger('eventDragStart', seg.el[0], seg.event, ev, {}); // last argument is jqui dummy
    },


    // Called after event segment dragging stops
    segDragStop: function(seg, ev) {
        this.isDraggingSeg = false;
        this.view.trigger('eventDragStop', seg.el[0], seg.event, ev, {}); // last argument is jqui dummy
    },


    // Given the cell an event drag began, and the cell event was dropped, calculates the new start/end/allDay
    // values for the event. Subclasses may override and set additional properties to be used by renderDrag.
    // A falsy returned value indicates an invalid drop.
    computeEventDrop: function(startCell, endCell, event) {
        var calendar = this.view.calendar;
        var dragStart = startCell.start;
        var dragEnd = endCell.start;
        var delta;
        var dropLocation;

        if (dragStart.hasTime() === dragEnd.hasTime()) {
            delta = this.diffDates(dragEnd, dragStart);

            // if an all-day event was in a timed area and it was dragged to a different time,
            // guarantee an end and adjust start/end to have times
            if (event.allDay && durationHasTime(delta)) {
                dropLocation = {
                    start: event.start.clone(),
                    end: calendar.getEventEnd(event), // will be an ambig day
                    allDay: false // for normalizeEventRangeTimes
                };
                calendar.normalizeEventRangeTimes(dropLocation);
            }
            // othewise, work off existing values
            else {
                dropLocation = {
                    start: event.start.clone(),
                    end: event.end ? event.end.clone() : null,
                    allDay: event.allDay // keep it the same
                };
            }

            dropLocation.start.add(delta);
            if (dropLocation.end) {
                dropLocation.end.add(delta);
            }
        }
        else {
            // if switching from day <-> timed, start should be reset to the dropped date, and the end cleared
            dropLocation = {
                start: dragEnd.clone(),
                end: null, // end should be cleared
                allDay: !dragEnd.hasTime()
            };
        }

        return dropLocation;
    },


    // Utility for apply dragOpacity to a jQuery set
    applyDragOpacity: function(els) {
        var opacity = this.view.opt('dragOpacity');

        if (opacity != null) {
            els.each(function(i, node) {
                // Don't use jQuery (will set an IE filter), do it the old fashioned way.
                // In IE8, a helper element will disappears if there's a filter.
                node.style.opacity = opacity;
            });
        }
    },


    /* External Element Dragging
    ------------------------------------------------------------------------------------------------------------------*/


    // Called when a jQuery UI drag is initiated anywhere in the DOM
    externalDragStart: function(ev, ui) {
        var view = this.view;
        var el;
        var accept;

        if (view.opt('droppable')) { // only listen if this setting is on
            el = $((ui ? ui.item : null) || ev.target);

            // Test that the dragged element passes the dropAccept selector or filter function.
            // FYI, the default is "*" (matches all)
            accept = view.opt('dropAccept');
            if ($.isFunction(accept) ? accept.call(el[0], el) : el.is(accept)) {
                if (!this.isDraggingExternal) { // prevent double-listening if fired twice
                    this.listenToExternalDrag(el, ev, ui);
                }
            }
        }
    },


    // Called when a jQuery UI drag starts and it needs to be monitored for cell dropping
    listenToExternalDrag: function(el, ev, ui) {
        var _this = this;
        var meta = getDraggedElMeta(el); // extra data about event drop, including possible event to create
        var dragListener;
        var dropLocation; // a null value signals an unsuccessful drag

        // listener that tracks mouse movement over date-associated pixel regions
        dragListener = new CellDragListener(this.coordMap, {
            listenStart: function() {
                _this.isDraggingExternal = true;
            },
            cellOver: function(cell) {
                dropLocation = _this.computeExternalDrop(cell, meta);
                if (dropLocation) {
                    _this.renderDrag(dropLocation); // called without a seg parameter
                }
                else { // invalid drop cell
                    disableCursor();
                }
            },
            cellOut: function() {
                dropLocation = null; // signal unsuccessful
                _this.unrenderDrag();
                enableCursor();
            },
            dragStop: function() {
                _this.unrenderDrag();
                enableCursor();

                if (dropLocation) { // element was dropped on a valid date/time cell
                    _this.view.reportExternalDrop(meta, dropLocation, el, ev, ui);
                }
            },
            listenStop: function() {
                _this.isDraggingExternal = false;
            }
        });

        dragListener.startDrag(ev); // start listening immediately
    },


    // Given a cell to be dropped upon, and misc data associated with the jqui drag (guaranteed to be a plain object),
    // returns start/end dates for the event that would result from the hypothetical drop. end might be null.
    // Returning a null value signals an invalid drop cell.
    computeExternalDrop: function(cell, meta) {
        var dropLocation = {
            start: cell.start.clone(),
            end: null
        };

        // if dropped on an all-day cell, and element's metadata specified a time, set it
        if (meta.startTime && !dropLocation.start.hasTime()) {
            dropLocation.start.time(meta.startTime);
        }

        if (meta.duration) {
            dropLocation.end = dropLocation.start.clone().add(meta.duration);
        }

        if (!this.view.calendar.isExternalDropRangeAllowed(dropLocation, meta.eventProps)) {
            return null;
        }

        return dropLocation;
    },



    /* Drag Rendering (for both events and an external elements)
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of an event or external element being dragged.
    // `dropLocation` contains hypothetical start/end/allDay values the event would have if dropped. end can be null.
    // `seg` is the internal segment object that is being dragged. If dragging an external element, `seg` is null.
    // A truthy returned value indicates this method has rendered a helper element.
    renderDrag: function(dropLocation, seg) {
        // subclasses must implement
    },


    // Unrenders a visual indication of an event or external element being dragged
    unrenderDrag: function() {
        // subclasses must implement
    },


    /* Resizing
    ------------------------------------------------------------------------------------------------------------------*/


    // Called when the user does a mousedown on an event's resizer, which might lead to resizing.
    // Generic enough to work with any type of Grid.
    segResizeMousedown: function(seg, ev, isStart) {
        var _this = this;
        var view = this.view;
        var calendar = view.calendar;
        var el = seg.el;
        var event = seg.event;
        var eventEnd = calendar.getEventEnd(event);
        var dragListener;
        var resizeLocation; // falsy if invalid resize

        // Tracks mouse movement over the *grid's* coordinate map
        dragListener = new CellDragListener(this.coordMap, {
            distance: 5,
            scroll: view.opt('dragScroll'),
            subjectEl: el,
            dragStart: function(ev) {
                _this.triggerSegMouseout(seg, ev); // ensure a mouseout on the manipulated event has been reported
                _this.segResizeStart(seg, ev);
            },
            cellOver: function(cell, isOrig, origCell) {
                resizeLocation = isStart ?
                    _this.computeEventStartResize(origCell, cell, event) :
                    _this.computeEventEndResize(origCell, cell, event);

                if (resizeLocation) {
                    if (!calendar.isEventRangeAllowed(resizeLocation, event)) {
                        disableCursor();
                        resizeLocation = null;
                    }
                    // no change? (TODO: how does this work with timezones?)
                    else if (resizeLocation.start.isSame(event.start) && resizeLocation.end.isSame(eventEnd)) {
                        resizeLocation = null;
                    }
                }

                if (resizeLocation) {
                    view.hideEvent(event);
                    _this.renderEventResize(resizeLocation, seg);
                }
            },
            cellOut: function() { // called before mouse moves to a different cell OR moved out of all cells
                resizeLocation = null;
            },
            cellDone: function() { // resets the rendering to show the original event
                _this.unrenderEventResize();
                view.showEvent(event);
                enableCursor();
            },
            dragStop: function(ev) {
                _this.segResizeStop(seg, ev);

                if (resizeLocation) { // valid date to resize to?
                    view.reportEventResize(event, resizeLocation, this.largeUnit, el, ev);
                }
            }
        });

        dragListener.mousedown(ev); // start listening, which will eventually lead to a dragStart
    },


    // Called before event segment resizing starts
    segResizeStart: function(seg, ev) {
        this.isResizingSeg = true;
        this.view.trigger('eventResizeStart', seg.el[0], seg.event, ev, {}); // last argument is jqui dummy
    },


    // Called after event segment resizing stops
    segResizeStop: function(seg, ev) {
        this.isResizingSeg = false;
        this.view.trigger('eventResizeStop', seg.el[0], seg.event, ev, {}); // last argument is jqui dummy
    },


    // Returns new date-information for an event segment being resized from its start
    computeEventStartResize: function(startCell, endCell, event) {
        return this.computeEventResize('start', startCell, endCell, event);
    },


    // Returns new date-information for an event segment being resized from its end
    computeEventEndResize: function(startCell, endCell, event) {
        return this.computeEventResize('end', startCell, endCell, event);
    },


    // Returns new date-information for an event segment being resized from its start OR end
    // `type` is either 'start' or 'end'
    computeEventResize: function(type, startCell, endCell, event) {
        var calendar = this.view.calendar;
        var delta = this.diffDates(endCell[type], startCell[type]);
        var range;
        var defaultDuration;

        // build original values to work from, guaranteeing a start and end
        range = {
            start: event.start.clone(),
            end: calendar.getEventEnd(event),
            allDay: event.allDay
        };

        // if an all-day event was in a timed area and was resized to a time, adjust start/end to have times
        if (range.allDay && durationHasTime(delta)) {
            range.allDay = false;
            calendar.normalizeEventRangeTimes(range);
        }

        range[type].add(delta); // apply delta to start or end

        // if the event was compressed too small, find a new reasonable duration for it
        if (!range.start.isBefore(range.end)) {

            defaultDuration = event.allDay ?
                calendar.defaultAllDayEventDuration :
                calendar.defaultTimedEventDuration;

            // between the cell's duration and the event's default duration, use the smaller of the two.
            // example: if year-length slots, and compressed to one slot, we don't want the event to be a year long
            if (this.cellDuration && this.cellDuration < defaultDuration) {
                defaultDuration = this.cellDuration;
            }

            if (type == 'start') { // resizing the start?
                range.start = range.end.clone().subtract(defaultDuration);
            }
            else { // resizing the end?
                range.end = range.start.clone().add(defaultDuration);
            }
        }

        return range;
    },


    // Renders a visual indication of an event being resized.
    // `range` has the updated dates of the event. `seg` is the original segment object involved in the drag.
    renderEventResize: function(range, seg) {
        // subclasses must implement
    },


    // Unrenders a visual indication of an event being resized.
    unrenderEventResize: function() {
        // subclasses must implement
    },


    /* Rendering Utils
    ------------------------------------------------------------------------------------------------------------------*/


    // Compute the text that should be displayed on an event's element.
    // `range` can be the Event object itself, or something range-like, with at least a `start`.
    // If event times are disabled, or the event has no time, will return a blank string.
    // If not specified, formatStr will default to the eventTimeFormat setting,
    // and displayEnd will default to the displayEventEnd setting.
    getEventTimeText: function(range, formatStr, displayEnd) {

        if (formatStr == null) {
            formatStr = this.eventTimeFormat;
        }

        if (displayEnd == null) {
            displayEnd = this.displayEventEnd;
        }

        if (this.displayEventTime && range.start.hasTime()) {
            if (displayEnd && range.end) {
                return this.view.formatRange(range, formatStr);
            }
            else {
                return range.start.format(formatStr);
            }
        }

        return '';
    },


    // Generic utility for generating the HTML classNames for an event segment's element
    getSegClasses: function(seg, isDraggable, isResizable) {
        var event = seg.event;
        var classes = [
            'fc-event',
            seg.isStart ? 'fc-start' : 'fc-not-start',
            seg.isEnd ? 'fc-end' : 'fc-not-end'
        ].concat(
            event.className,
            event.source ? event.source.className : []
        );

        if (isDraggable) {
            classes.push('fc-draggable');
        }
        if (isResizable) {
            classes.push('fc-resizable');
        }

        return classes;
    },


    // Utility for generating event skin-related CSS properties
    getEventSkinCss: function(event) {
        var view = this.view;
        var source = event.source || {};
        var eventColor = event.color;
        var sourceColor = source.color;
        var optionColor = view.opt('eventColor');

        return {
            'background-color':
                event.backgroundColor ||
                eventColor ||
                source.backgroundColor ||
                sourceColor ||
                view.opt('eventBackgroundColor') ||
                optionColor,
            'border-color':
                event.borderColor ||
                eventColor ||
                source.borderColor ||
                sourceColor ||
                view.opt('eventBorderColor') ||
                optionColor,
            color:
                event.textColor ||
                source.textColor ||
                view.opt('eventTextColor')
        };
    },


    /* Converting events -> ranges -> segs
    ------------------------------------------------------------------------------------------------------------------*/


    // Converts an array of event objects into an array of event segment objects.
    // A custom `rangeToSegsFunc` may be given for arbitrarily slicing up events.
    // Doesn't guarantee an order for the resulting array.
    eventsToSegs: function(events, rangeToSegsFunc) {
        var eventRanges = this.eventsToRanges(events);
        var segs = [];
        var i;

        for (i = 0; i < eventRanges.length; i++) {
            segs.push.apply(
                segs,
                this.eventRangeToSegs(eventRanges[i], rangeToSegsFunc)
            );
        }

        return segs;
    },


    // Converts an array of events into an array of "range" objects.
    // A "range" object is a plain object with start/end properties denoting the time it covers. Also an event property.
    // For "normal" events, this will be identical to the event's start/end, but for "inverse-background" events,
    // will create an array of ranges that span the time *not* covered by the given event.
    // Doesn't guarantee an order for the resulting array.
    eventsToRanges: function(events) {
        var _this = this;
        var eventsById = groupEventsById(events);
        var ranges = [];

        // group by ID so that related inverse-background events can be rendered together
        $.each(eventsById, function(id, eventGroup) {
            if (eventGroup.length) {
                ranges.push.apply(
                    ranges,
                    isInverseBgEvent(eventGroup[0]) ?
                        _this.eventsToInverseRanges(eventGroup) :
                        _this.eventsToNormalRanges(eventGroup)
                );
            }
        });

        return ranges;
    },


    // Converts an array of "normal" events (not inverted rendering) into a parallel array of ranges
    eventsToNormalRanges: function(events) {
        var calendar = this.view.calendar;
        var ranges = [];
        var i, event;
        var eventStart, eventEnd;

        for (i = 0; i < events.length; i++) {
            event = events[i];

            // make copies and normalize by stripping timezone
            eventStart = event.start.clone().stripZone();
            eventEnd = calendar.getEventEnd(event).stripZone();

            ranges.push({
                event: event,
                start: eventStart,
                end: eventEnd,
                eventStartMS: +eventStart,
                eventDurationMS: eventEnd - eventStart
            });
        }

        return ranges;
    },


    // Converts an array of events, with inverse-background rendering, into an array of range objects.
    // The range objects will cover all the time NOT covered by the events.
    eventsToInverseRanges: function(events) {
        var view = this.view;
        var viewStart = view.start.clone().stripZone(); // normalize timezone
        var viewEnd = view.end.clone().stripZone(); // normalize timezone
        var normalRanges = this.eventsToNormalRanges(events); // will give us normalized dates we can use w/o copies
        var inverseRanges = [];
        var event0 = events[0]; // assign this to each range's `.event`
        var start = viewStart; // the end of the previous range. the start of the new range
        var i, normalRange;

        // ranges need to be in order. required for our date-walking algorithm
        normalRanges.sort(compareNormalRanges);

        for (i = 0; i < normalRanges.length; i++) {
            normalRange = normalRanges[i];

            // add the span of time before the event (if there is any)
            if (normalRange.start > start) { // compare millisecond time (skip any ambig logic)
                inverseRanges.push({
                    event: event0,
                    start: start,
                    end: normalRange.start
                });
            }

            start = normalRange.end;
        }

        // add the span of time after the last event (if there is any)
        if (start < viewEnd) { // compare millisecond time (skip any ambig logic)
            inverseRanges.push({
                event: event0,
                start: start,
                end: viewEnd
            });
        }

        return inverseRanges;
    },


    // Slices the given event range into one or more segment objects.
    // A `rangeToSegsFunc` custom slicing function can be given.
    eventRangeToSegs: function(eventRange, rangeToSegsFunc) {
        var segs;
        var i, seg;

        eventRange = this.view.calendar.ensureVisibleEventRange(eventRange);

        if (rangeToSegsFunc) {
            segs = rangeToSegsFunc(eventRange);
        }
        else {
            segs = this.rangeToSegs(eventRange); // defined by the subclass
        }

        for (i = 0; i < segs.length; i++) {
            seg = segs[i];
            seg.event = eventRange.event;
            seg.eventStartMS = eventRange.eventStartMS;
            seg.eventDurationMS = eventRange.eventDurationMS;
        }

        return segs;
    },


    sortSegs: function(segs) {
        segs.sort(proxy(this, 'compareSegs'));
    },


    // A cmp function for determining which segments should take visual priority
    // DOES NOT WORK ON INVERTED BACKGROUND EVENTS because they have no eventStartMS/eventDurationMS
    compareSegs: function(seg1, seg2) {
        return seg1.eventStartMS - seg2.eventStartMS || // earlier events go first
            seg2.eventDurationMS - seg1.eventDurationMS || // tie? longer events go first
            seg2.event.allDay - seg1.event.allDay || // tie? put all-day events first (booleans cast to 0/1)
            compareByFieldSpecs(seg1.event, seg2.event, this.view.eventOrderSpecs);
    }

});


/* Utilities
----------------------------------------------------------------------------------------------------------------------*/


function isBgEvent(event) { // returns true if background OR inverse-background
    var rendering = getEventRendering(event);
    return rendering === 'background' || rendering === 'inverse-background';
}


function isInverseBgEvent(event) {
    return getEventRendering(event) === 'inverse-background';
}


function getEventRendering(event) {
    return firstDefined((event.source || {}).rendering, event.rendering);
}


function groupEventsById(events) {
    var eventsById = {};
    var i, event;

    for (i = 0; i < events.length; i++) {
        event = events[i];
        (eventsById[event._id] || (eventsById[event._id] = [])).push(event);
    }

    return eventsById;
}


// A cmp function for determining which non-inverted "ranges" (see above) happen earlier
function compareNormalRanges(range1, range2) {
    return range1.eventStartMS - range2.eventStartMS; // earlier ranges go first
}


/* External-Dragging-Element Data
----------------------------------------------------------------------------------------------------------------------*/

// Require all HTML5 data-* attributes used by FullCalendar to have this prefix.
// A value of '' will query attributes like data-event. A value of 'fc' will query attributes like data-fc-event.
fc.dataAttrPrefix = '';

// Given a jQuery element that might represent a dragged FullCalendar event, returns an intermediate data structure
// to be used for Event Object creation.
// A defined `.eventProps`, even when empty, indicates that an event should be created.
function getDraggedElMeta(el) {
    var prefix = fc.dataAttrPrefix;
    var eventProps; // properties for creating the event, not related to date/time
    var startTime; // a Duration
    var duration;
    var stick;

    if (prefix) { prefix += '-'; }
    eventProps = el.data(prefix + 'event') || null;

    if (eventProps) {
        if (typeof eventProps === 'object') {
            eventProps = $.extend({}, eventProps); // make a copy
        }
        else { // something like 1 or true. still signal event creation
            eventProps = {};
        }

        // pluck special-cased date/time properties
        startTime = eventProps.start;
        if (startTime == null) { startTime = eventProps.time; } // accept 'time' as well
        duration = eventProps.duration;
        stick = eventProps.stick;
        delete eventProps.start;
        delete eventProps.time;
        delete eventProps.duration;
        delete eventProps.stick;
    }

    // fallback to standalone attribute values for each of the date/time properties
    if (startTime == null) { startTime = el.data(prefix + 'start'); }
    if (startTime == null) { startTime = el.data(prefix + 'time'); } // accept 'time' as well
    if (duration == null) { duration = el.data(prefix + 'duration'); }
    if (stick == null) { stick = el.data(prefix + 'stick'); }

    // massage into correct data types
    startTime = startTime != null ? moment.duration(startTime) : null;
    duration = duration != null ? moment.duration(duration) : null;
    stick = Boolean(stick);

    return { eventProps: eventProps, startTime: startTime, duration: duration, stick: stick };
}




/* A component that renders a grid of whole-days that runs horizontally. There can be multiple rows, one per week.
----------------------------------------------------------------------------------------------------------------------*/

var DayGrid = Grid.extend({

    numbersVisible: false, // should render a row for day/week numbers? set by outside view. TODO: make internal
    bottomCoordPadding: 0, // hack for extending the hit area for the last row of the coordinate grid
    breakOnWeeks: null, // should create a new row for each week? set by outside view

    cellDates: null, // flat chronological array of each cell's dates
    dayToCellOffsets: null, // maps days offsets from grid's start date, to cell offsets

    rowEls: null, // set of fake row elements
    dayEls: null, // set of whole-day elements comprising the row's background
    helperEls: null, // set of cell skeleton elements for rendering the mock event "helper"


    constructor: function() {
        Grid.apply(this, arguments);

        this.cellDuration = moment.duration(1, 'day'); // for Grid system
    },


    // Renders the rows and columns into the component's `this.el`, which should already be assigned.
    // isRigid determins whether the individual rows should ignore the contents and be a constant height.
    // Relies on the view's colCnt and rowCnt. In the future, this component should probably be self-sufficient.
    renderDates: function(isRigid) {
        var view = this.view;
        var rowCnt = this.rowCnt;
        var colCnt = this.colCnt;
        var cellCnt = rowCnt * colCnt;
        var html = '';
        var row;
        var i, cell;

        for (row = 0; row < rowCnt; row++) {
            html += this.dayRowHtml(row, isRigid);
        }
        this.el.html(html);

        this.rowEls = this.el.find('.fc-row');
        this.dayEls = this.el.find('.fc-day');

        // trigger dayRender with each cell's element
        for (i = 0; i < cellCnt; i++) {
            cell = this.getCell(i);
            view.trigger('dayRender', null, cell.start, this.dayEls.eq(i));
        }
    },


    unrenderDates: function() {
        this.removeSegPopover();
    },


    renderBusinessHours: function() {
        var events = this.view.calendar.getBusinessHoursEvents(true); // wholeDay=true
        var segs = this.eventsToSegs(events);

        this.renderFill('businessHours', segs, 'bgevent');
    },


    // Generates the HTML for a single row. `row` is the row number.
    dayRowHtml: function(row, isRigid) {
        var view = this.view;
        var classes = [ 'fc-row', 'fc-week', view.widgetContentClass ];

        if (isRigid) {
            classes.push('fc-rigid');
        }

        return '' +
            '<div class="' + classes.join(' ') + '">' +
                '<div class="fc-bg">' +
                    '<table>' +
                        this.rowHtml('day', row) + // leverages RowRenderer. calls dayCellHtml()
                    '</table>' +
                '</div>' +
                '<div class="fc-content-skeleton">' +
                    '<table>' +
                        (this.numbersVisible ?
                            '<thead>' +
                                this.rowHtml('number', row) + // leverages RowRenderer. View will define render method
                            '</thead>' :
                            ''
                            ) +
                    '</table>' +
                '</div>' +
            '</div>';
    },


    // Renders the HTML for a whole-day cell. Will eventually end up in the day-row's background.
    // We go through a 'day' row type instead of just doing a 'bg' row type so that the View can do custom rendering
    // specifically for whole-day rows, whereas a 'bg' might also be used for other purposes (TimeGrid bg for example).
    dayCellHtml: function(cell) {
        return this.bgCellHtml(cell);
    },


    /* Options
    ------------------------------------------------------------------------------------------------------------------*/


    // Computes a default column header formatting string if `colFormat` is not explicitly defined
    computeColHeadFormat: function() {
        if (this.rowCnt > 1) { // more than one week row. day numbers will be in each cell
            return 'ddd'; // "Sat"
        }
        else if (this.colCnt > 1) { // multiple days, so full single date string WON'T be in title text
            return this.view.opt('dayOfMonthFormat'); // "Sat 12/10"
        }
        else { // single day, so full single date string will probably be in title text
            return 'dddd'; // "Saturday"
        }
    },


    // Computes a default event time formatting string if `timeFormat` is not explicitly defined
    computeEventTimeFormat: function() {
        return this.view.opt('extraSmallTimeFormat'); // like "6p" or "6:30p"
    },


    // Computes a default `displayEventEnd` value if one is not expliclty defined
    computeDisplayEventEnd: function() {
        return this.colCnt == 1; // we'll likely have space if there's only one day
    },


    /* Cell System
    ------------------------------------------------------------------------------------------------------------------*/


    rangeUpdated: function() {
        var cellDates;
        var firstDay;
        var rowCnt;
        var colCnt;

        this.updateCellDates(); // populates cellDates and dayToCellOffsets
        cellDates = this.cellDates;

        if (this.breakOnWeeks) {
            // count columns until the day-of-week repeats
            firstDay = cellDates[0].day();
            for (colCnt = 1; colCnt < cellDates.length; colCnt++) {
                if (cellDates[colCnt].day() == firstDay) {
                    break;
                }
            }
            rowCnt = Math.ceil(cellDates.length / colCnt);
        }
        else {
            rowCnt = 1;
            colCnt = cellDates.length;
        }

        this.rowCnt = rowCnt;
        this.colCnt = colCnt;
    },


    // Populates cellDates and dayToCellOffsets
    updateCellDates: function() {
        var view = this.view;
        var date = this.start.clone();
        var dates = [];
        var offset = -1;
        var offsets = [];

        while (date.isBefore(this.end)) { // loop each day from start to end
            if (view.isHiddenDay(date)) {
                offsets.push(offset + 0.5); // mark that it's between offsets
            }
            else {
                offset++;
                offsets.push(offset);
                dates.push(date.clone());
            }
            date.add(1, 'days');
        }

        this.cellDates = dates;
        this.dayToCellOffsets = offsets;
    },


    // Given a cell object, generates its start date. Returns a reference-free copy.
    computeCellDate: function(cell) {
        var colCnt = this.colCnt;
        var index = cell.row * colCnt + (this.isRTL ? colCnt - cell.col - 1 : cell.col);

        return this.cellDates[index].clone();
    },


    // Retrieves the element representing the given row
    getRowEl: function(row) {
        return this.rowEls.eq(row);
    },


    // Retrieves the element representing the given column
    getColEl: function(col) {
        return this.dayEls.eq(col);
    },


    // Gets the whole-day element associated with the cell
    getCellDayEl: function(cell) {
        return this.dayEls.eq(cell.row * this.colCnt + cell.col);
    },


    // Overrides Grid's method for when row coordinates are computed
    computeRowCoords: function() {
        var rowCoords = Grid.prototype.computeRowCoords.call(this); // call the super-method

        // hack for extending last row (used by AgendaView)
        rowCoords[rowCoords.length - 1].bottom += this.bottomCoordPadding;

        return rowCoords;
    },


    /* Dates
    ------------------------------------------------------------------------------------------------------------------*/


    // Slices up a date range by row into an array of segments
    rangeToSegs: function(range) {
        var isRTL = this.isRTL;
        var rowCnt = this.rowCnt;
        var colCnt = this.colCnt;
        var segs = [];
        var first, last; // inclusive cell-offset range for given range
        var row;
        var rowFirst, rowLast; // inclusive cell-offset range for current row
        var isStart, isEnd;
        var segFirst, segLast; // inclusive cell-offset range for segment
        var seg;

        range = this.view.computeDayRange(range); // make whole-day range, considering nextDayThreshold
        first = this.dateToCellOffset(range.start);
        last = this.dateToCellOffset(range.end.subtract(1, 'days')); // offset of inclusive end date

        for (row = 0; row < rowCnt; row++) {
            rowFirst = row * colCnt;
            rowLast = rowFirst + colCnt - 1;

            // intersect segment's offset range with the row's
            segFirst = Math.max(rowFirst, first);
            segLast = Math.min(rowLast, last);

            // deal with in-between indices
            segFirst = Math.ceil(segFirst); // in-between starts round to next cell
            segLast = Math.floor(segLast); // in-between ends round to prev cell

            if (segFirst <= segLast) { // was there any intersection with the current row?

                // must be matching integers to be the segment's start/end
                isStart = segFirst === first;
                isEnd = segLast === last;

                // translate offsets to be relative to start-of-row
                segFirst -= rowFirst;
                segLast -= rowFirst;

                seg = { row: row, isStart: isStart, isEnd: isEnd };
                if (isRTL) {
                    seg.leftCol = colCnt - segLast - 1;
                    seg.rightCol = colCnt - segFirst - 1;
                }
                else {
                    seg.leftCol = segFirst;
                    seg.rightCol = segLast;
                }
                segs.push(seg);
            }
        }

        return segs;
    },


    // Given a date, returns its chronolocial cell-offset from the first cell of the grid.
    // If the date lies between cells (because of hiddenDays), returns a floating-point value between offsets.
    // If before the first offset, returns a negative number.
    // If after the last offset, returns an offset past the last cell offset.
    // Only works for *start* dates of cells. Will not work for exclusive end dates for cells.
    dateToCellOffset: function(date) {
        var offsets = this.dayToCellOffsets;
        var day = date.diff(this.start, 'days');

        if (day < 0) {
            return offsets[0] - 1;
        }
        else if (day >= offsets.length) {
            return offsets[offsets.length - 1] + 1;
        }
        else {
            return offsets[day];
        }
    },


    /* Event Drag Visualization
    ------------------------------------------------------------------------------------------------------------------*/
    // TODO: move to DayGrid.event, similar to what we did with Grid's drag methods


    // Renders a visual indication of an event or external element being dragged.
    // The dropLocation's end can be null. seg can be null. See Grid::renderDrag for more info.
    renderDrag: function(dropLocation, seg) {

        // always render a highlight underneath
        this.renderHighlight(this.eventRangeToSegs(dropLocation));

        // if a segment from the same calendar but another component is being dragged, render a helper event
        if (seg && !seg.el.closest(this.el).length) {

            this.renderRangeHelper(dropLocation, seg);
            this.applyDragOpacity(this.helperEls);

            return true; // a helper has been rendered
        }
    },


    // Unrenders any visual indication of a hovering event
    unrenderDrag: function() {
        this.unrenderHighlight();
        this.unrenderHelper();
    },


    /* Event Resize Visualization
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of an event being resized
    renderEventResize: function(range, seg) {
        this.renderHighlight(this.eventRangeToSegs(range));
        this.renderRangeHelper(range, seg);
    },


    // Unrenders a visual indication of an event being resized
    unrenderEventResize: function() {
        this.unrenderHighlight();
        this.unrenderHelper();
    },


    /* Event Helper
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a mock "helper" event. `sourceSeg` is the associated internal segment object. It can be null.
    renderHelper: function(event, sourceSeg) {
        var helperNodes = [];
        var segs = this.eventsToSegs([ event ]);
        var rowStructs;

        segs = this.renderFgSegEls(segs); // assigns each seg's el and returns a subset of segs that were rendered
        rowStructs = this.renderSegRows(segs);

        // inject each new event skeleton into each associated row
        this.rowEls.each(function(row, rowNode) {
            var rowEl = $(rowNode); // the .fc-row
            var skeletonEl = $('<div class="fc-helper-skeleton"><table/></div>'); // will be absolutely positioned
            var skeletonTop;

            // If there is an original segment, match the top position. Otherwise, put it at the row's top level
            if (sourceSeg && sourceSeg.row === row) {
                skeletonTop = sourceSeg.el.position().top;
            }
            else {
                skeletonTop = rowEl.find('.fc-content-skeleton tbody').position().top;
            }

            skeletonEl.css('top', skeletonTop)
                .find('table')
                    .append(rowStructs[row].tbodyEl);

            rowEl.append(skeletonEl);
            helperNodes.push(skeletonEl[0]);
        });

        this.helperEls = $(helperNodes); // array -> jQuery set
    },


    // Unrenders any visual indication of a mock helper event
    unrenderHelper: function() {
        if (this.helperEls) {
            this.helperEls.remove();
            this.helperEls = null;
        }
    },


    /* Fill System (highlight, background events, business hours)
    ------------------------------------------------------------------------------------------------------------------*/


    fillSegTag: 'td', // override the default tag name


    // Renders a set of rectangles over the given segments of days.
    // Only returns segments that successfully rendered.
    renderFill: function(type, segs, className) {
        var nodes = [];
        var i, seg;
        var skeletonEl;

        segs = this.renderFillSegEls(type, segs); // assignes `.el` to each seg. returns successfully rendered segs

        for (i = 0; i < segs.length; i++) {
            seg = segs[i];
            skeletonEl = this.renderFillRow(type, seg, className);
            this.rowEls.eq(seg.row).append(skeletonEl);
            nodes.push(skeletonEl[0]);
        }

        this.elsByFill[type] = $(nodes);

        return segs;
    },


    // Generates the HTML needed for one row of a fill. Requires the seg's el to be rendered.
    renderFillRow: function(type, seg, className) {
        var colCnt = this.colCnt;
        var startCol = seg.leftCol;
        var endCol = seg.rightCol + 1;
        var skeletonEl;
        var trEl;

        className = className || type.toLowerCase();

        skeletonEl = $(
            '<div class="fc-' + className + '-skeleton">' +
                '<table><tr/></table>' +
            '</div>'
        );
        trEl = skeletonEl.find('tr');

        if (startCol > 0) {
            trEl.append('<td colspan="' + startCol + '"/>');
        }

        trEl.append(
            seg.el.attr('colspan', endCol - startCol)
        );

        if (endCol < colCnt) {
            trEl.append('<td colspan="' + (colCnt - endCol) + '"/>');
        }

        this.bookendCells(trEl, type);

        return skeletonEl;
    }

});



/* Event-rendering methods for the DayGrid class
----------------------------------------------------------------------------------------------------------------------*/

DayGrid.mixin({

    rowStructs: null, // an array of objects, each holding information about a row's foreground event-rendering


    // Unrenders all events currently rendered on the grid
    unrenderEvents: function() {
        this.removeSegPopover(); // removes the "more.." events popover
        Grid.prototype.unrenderEvents.apply(this, arguments); // calls the super-method
    },


    // Retrieves all rendered segment objects currently rendered on the grid
    getEventSegs: function() {
        return Grid.prototype.getEventSegs.call(this) // get the segments from the super-method
            .concat(this.popoverSegs || []); // append the segments from the "more..." popover
    },


    // Renders the given background event segments onto the grid
    renderBgSegs: function(segs) {

        // don't render timed background events
        var allDaySegs = $.grep(segs, function(seg) {
            return seg.event.allDay;
        });

        return Grid.prototype.renderBgSegs.call(this, allDaySegs); // call the super-method
    },


    // Renders the given foreground event segments onto the grid
    renderFgSegs: function(segs) {
        var rowStructs;

        // render an `.el` on each seg
        // returns a subset of the segs. segs that were actually rendered
        segs = this.renderFgSegEls(segs);

        rowStructs = this.rowStructs = this.renderSegRows(segs);

        // append to each row's content skeleton
        this.rowEls.each(function(i, rowNode) {
            $(rowNode).find('.fc-content-skeleton > table').append(
                rowStructs[i].tbodyEl
            );
        });

        return segs; // return only the segs that were actually rendered
    },


    // Unrenders all currently rendered foreground event segments
    unrenderFgSegs: function() {
        var rowStructs = this.rowStructs || [];
        var rowStruct;

        while ((rowStruct = rowStructs.pop())) {
            rowStruct.tbodyEl.remove();
        }

        this.rowStructs = null;
    },


    // Uses the given events array to generate <tbody> elements that should be appended to each row's content skeleton.
    // Returns an array of rowStruct objects (see the bottom of `renderSegRow`).
    // PRECONDITION: each segment shoud already have a rendered and assigned `.el`
    renderSegRows: function(segs) {
        var rowStructs = [];
        var segRows;
        var row;

        segRows = this.groupSegRows(segs); // group into nested arrays

        // iterate each row of segment groupings
        for (row = 0; row < segRows.length; row++) {
            rowStructs.push(
                this.renderSegRow(row, segRows[row])
            );
        }

        return rowStructs;
    },


    // Builds the HTML to be used for the default element for an individual segment
    fgSegHtml: function(seg, disableResizing) {
        var view = this.view;
        var event = seg.event;
        var isDraggable = view.isEventDraggable(event);
        var isResizableFromStart = !disableResizing && event.allDay &&
            seg.isStart && view.isEventResizableFromStart(event);
        var isResizableFromEnd = !disableResizing && event.allDay &&
            seg.isEnd && view.isEventResizableFromEnd(event);
        var classes = this.getSegClasses(seg, isDraggable, isResizableFromStart || isResizableFromEnd);
        var skinCss = cssToStr(this.getEventSkinCss(event));
        var timeHtml = '';
        var timeText;
        var titleHtml;

        classes.unshift('fc-day-grid-event', 'fc-h-event');

        // Only display a timed events time if it is the starting segment
        if (seg.isStart) {
            timeText = this.getEventTimeText(event);
            if (timeText) {
                timeHtml = '<span class="fc-time">' + htmlEscape(timeText) + '</span>';
            }
        }

        titleHtml =
            '<span class="fc-title">' +
                (htmlEscape(event.title || '') || '&nbsp;') + // we always want one line of height
            '</span>';
        
        return '<a class="' + classes.join(' ') + '"' +
                (event.url ?
                    ' href="' + htmlEscape(event.url) + '"' :
                    ''
                    ) +
                (skinCss ?
                    ' style="' + skinCss + '"' :
                    ''
                    ) +
            '>' +
                '<div class="fc-content">' +
                    (this.isRTL ?
                        titleHtml + ' ' + timeHtml : // put a natural space in between
                        timeHtml + ' ' + titleHtml   //
                        ) +
                '</div>' +
                (isResizableFromStart ?
                    '<div class="fc-resizer fc-start-resizer" />' :
                    ''
                    ) +
                (isResizableFromEnd ?
                    '<div class="fc-resizer fc-end-resizer" />' :
                    ''
                    ) +
            '</a>';
    },


    // Given a row # and an array of segments all in the same row, render a <tbody> element, a skeleton that contains
    // the segments. Returns object with a bunch of internal data about how the render was calculated.
    // NOTE: modifies rowSegs
    renderSegRow: function(row, rowSegs) {
        var colCnt = this.colCnt;
        var segLevels = this.buildSegLevels(rowSegs); // group into sub-arrays of levels
        var levelCnt = Math.max(1, segLevels.length); // ensure at least one level
        var tbody = $('<tbody/>');
        var segMatrix = []; // lookup for which segments are rendered into which level+col cells
        var cellMatrix = []; // lookup for all <td> elements of the level+col matrix
        var loneCellMatrix = []; // lookup for <td> elements that only take up a single column
        var i, levelSegs;
        var col;
        var tr;
        var j, seg;
        var td;

        // populates empty cells from the current column (`col`) to `endCol`
        function emptyCellsUntil(endCol) {
            while (col < endCol) {
                // try to grab a cell from the level above and extend its rowspan. otherwise, create a fresh cell
                td = (loneCellMatrix[i - 1] || [])[col];
                if (td) {
                    td.attr(
                        'rowspan',
                        parseInt(td.attr('rowspan') || 1, 10) + 1
                    );
                }
                else {
                    td = $('<td/>');
                    tr.append(td);
                }
                cellMatrix[i][col] = td;
                loneCellMatrix[i][col] = td;
                col++;
            }
        }

        for (i = 0; i < levelCnt; i++) { // iterate through all levels
            levelSegs = segLevels[i];
            col = 0;
            tr = $('<tr/>');

            segMatrix.push([]);
            cellMatrix.push([]);
            loneCellMatrix.push([]);

            // levelCnt might be 1 even though there are no actual levels. protect against this.
            // this single empty row is useful for styling.
            if (levelSegs) {
                for (j = 0; j < levelSegs.length; j++) { // iterate through segments in level
                    seg = levelSegs[j];

                    emptyCellsUntil(seg.leftCol);

                    // create a container that occupies or more columns. append the event element.
                    td = $('<td class="fc-event-container"/>').append(seg.el);
                    if (seg.leftCol != seg.rightCol) {
                        td.attr('colspan', seg.rightCol - seg.leftCol + 1);
                    }
                    else { // a single-column segment
                        loneCellMatrix[i][col] = td;
                    }

                    while (col <= seg.rightCol) {
                        cellMatrix[i][col] = td;
                        segMatrix[i][col] = seg;
                        col++;
                    }

                    tr.append(td);
                }
            }

            emptyCellsUntil(colCnt); // finish off the row
            this.bookendCells(tr, 'eventSkeleton');
            tbody.append(tr);
        }

        return { // a "rowStruct"
            row: row, // the row number
            tbodyEl: tbody,
            cellMatrix: cellMatrix,
            segMatrix: segMatrix,
            segLevels: segLevels,
            segs: rowSegs
        };
    },


    // Stacks a flat array of segments, which are all assumed to be in the same row, into subarrays of vertical levels.
    // NOTE: modifies segs
    buildSegLevels: function(segs) {
        var levels = [];
        var i, seg;
        var j;

        // Give preference to elements with certain criteria, so they have
        // a chance to be closer to the top.
        this.sortSegs(segs);
        
        for (i = 0; i < segs.length; i++) {
            seg = segs[i];

            // loop through levels, starting with the topmost, until the segment doesn't collide with other segments
            for (j = 0; j < levels.length; j++) {
                if (!isDaySegCollision(seg, levels[j])) {
                    break;
                }
            }
            // `j` now holds the desired subrow index
            seg.level = j;

            // create new level array if needed and append segment
            (levels[j] || (levels[j] = [])).push(seg);
        }

        // order segments left-to-right. very important if calendar is RTL
        for (j = 0; j < levels.length; j++) {
            levels[j].sort(compareDaySegCols);
        }

        return levels;
    },


    // Given a flat array of segments, return an array of sub-arrays, grouped by each segment's row
    groupSegRows: function(segs) {
        var segRows = [];
        var i;

        for (i = 0; i < this.rowCnt; i++) {
            segRows.push([]);
        }

        for (i = 0; i < segs.length; i++) {
            segRows[segs[i].row].push(segs[i]);
        }

        return segRows;
    }

});


// Computes whether two segments' columns collide. They are assumed to be in the same row.
function isDaySegCollision(seg, otherSegs) {
    var i, otherSeg;

    for (i = 0; i < otherSegs.length; i++) {
        otherSeg = otherSegs[i];

        if (
            otherSeg.leftCol <= seg.rightCol &&
            otherSeg.rightCol >= seg.leftCol
        ) {
            return true;
        }
    }

    return false;
}


// A cmp function for determining the leftmost event
function compareDaySegCols(a, b) {
    return a.leftCol - b.leftCol;
}



/* Methods relate to limiting the number events for a given day on a DayGrid
----------------------------------------------------------------------------------------------------------------------*/
// NOTE: all the segs being passed around in here are foreground segs

DayGrid.mixin({

    segPopover: null, // the Popover that holds events that can't fit in a cell. null when not visible
    popoverSegs: null, // an array of segment objects that the segPopover holds. null when not visible


    removeSegPopover: function() {
        if (this.segPopover) {
            this.segPopover.hide(); // in handler, will call segPopover's removeElement
        }
    },


    // Limits the number of "levels" (vertically stacking layers of events) for each row of the grid.
    // `levelLimit` can be false (don't limit), a number, or true (should be computed).
    limitRows: function(levelLimit) {
        var rowStructs = this.rowStructs || [];
        var row; // row #
        var rowLevelLimit;

        for (row = 0; row < rowStructs.length; row++) {
            this.unlimitRow(row);

            if (!levelLimit) {
                rowLevelLimit = false;
            }
            else if (typeof levelLimit === 'number') {
                rowLevelLimit = levelLimit;
            }
            else {
                rowLevelLimit = this.computeRowLevelLimit(row);
            }

            if (rowLevelLimit !== false) {
                this.limitRow(row, rowLevelLimit);
            }
        }
    },


    // Computes the number of levels a row will accomodate without going outside its bounds.
    // Assumes the row is "rigid" (maintains a constant height regardless of what is inside).
    // `row` is the row number.
    computeRowLevelLimit: function(row) {
        var rowEl = this.rowEls.eq(row); // the containing "fake" row div
        var rowHeight = rowEl.height(); // TODO: cache somehow?
        var trEls = this.rowStructs[row].tbodyEl.children();
        var i, trEl;
        var trHeight;

        function iterInnerHeights(i, childNode) {
            trHeight = Math.max(trHeight, $(childNode).outerHeight());
        }

        // Reveal one level <tr> at a time and stop when we find one out of bounds
        for (i = 0; i < trEls.length; i++) {
            trEl = trEls.eq(i).removeClass('fc-limited'); // reset to original state (reveal)

            // with rowspans>1 and IE8, trEl.outerHeight() would return the height of the largest cell,
            // so instead, find the tallest inner content element.
            trHeight = 0;
            trEl.find('> td > :first-child').each(iterInnerHeights);

            if (trEl.position().top + trHeight > rowHeight) {
                return i;
            }
        }

        return false; // should not limit at all
    },


    // Limits the given grid row to the maximum number of levels and injects "more" links if necessary.
    // `row` is the row number.
    // `levelLimit` is a number for the maximum (inclusive) number of levels allowed.
    limitRow: function(row, levelLimit) {
        var _this = this;
        var rowStruct = this.rowStructs[row];
        var moreNodes = []; // array of "more" <a> links and <td> DOM nodes
        var col = 0; // col #, left-to-right (not chronologically)
        var cell;
        var levelSegs; // array of segment objects in the last allowable level, ordered left-to-right
        var cellMatrix; // a matrix (by level, then column) of all <td> jQuery elements in the row
        var limitedNodes; // array of temporarily hidden level <tr> and segment <td> DOM nodes
        var i, seg;
        var segsBelow; // array of segment objects below `seg` in the current `col`
        var totalSegsBelow; // total number of segments below `seg` in any of the columns `seg` occupies
        var colSegsBelow; // array of segment arrays, below seg, one for each column (offset from segs's first column)
        var td, rowspan;
        var segMoreNodes; // array of "more" <td> cells that will stand-in for the current seg's cell
        var j;
        var moreTd, moreWrap, moreLink;

        // Iterates through empty level cells and places "more" links inside if need be
        function emptyCellsUntil(endCol) { // goes from current `col` to `endCol`
            while (col < endCol) {
                cell = _this.getCell(row, col);
                segsBelow = _this.getCellSegs(cell, levelLimit);
                if (segsBelow.length) {
                    td = cellMatrix[levelLimit - 1][col];
                    moreLink = _this.renderMoreLink(cell, segsBelow);
                    moreWrap = $('<div/>').append(moreLink);
                    td.append(moreWrap);
                    moreNodes.push(moreWrap[0]);
                }
                col++;
            }
        }

        if (levelLimit && levelLimit < rowStruct.segLevels.length) { // is it actually over the limit?
            levelSegs = rowStruct.segLevels[levelLimit - 1];
            cellMatrix = rowStruct.cellMatrix;

            limitedNodes = rowStruct.tbodyEl.children().slice(levelLimit) // get level <tr> elements past the limit
                .addClass('fc-limited').get(); // hide elements and get a simple DOM-nodes array

            // iterate though segments in the last allowable level
            for (i = 0; i < levelSegs.length; i++) {
                seg = levelSegs[i];
                emptyCellsUntil(seg.leftCol); // process empty cells before the segment

                // determine *all* segments below `seg` that occupy the same columns
                colSegsBelow = [];
                totalSegsBelow = 0;
                while (col <= seg.rightCol) {
                    cell = this.getCell(row, col);
                    segsBelow = this.getCellSegs(cell, levelLimit);
                    colSegsBelow.push(segsBelow);
                    totalSegsBelow += segsBelow.length;
                    col++;
                }

                if (totalSegsBelow) { // do we need to replace this segment with one or many "more" links?
                    td = cellMatrix[levelLimit - 1][seg.leftCol]; // the segment's parent cell
                    rowspan = td.attr('rowspan') || 1;
                    segMoreNodes = [];

                    // make a replacement <td> for each column the segment occupies. will be one for each colspan
                    for (j = 0; j < colSegsBelow.length; j++) {
                        moreTd = $('<td class="fc-more-cell"/>').attr('rowspan', rowspan);
                        segsBelow = colSegsBelow[j];
                        cell = this.getCell(row, seg.leftCol + j);
                        moreLink = this.renderMoreLink(cell, [ seg ].concat(segsBelow)); // count seg as hidden too
                        moreWrap = $('<div/>').append(moreLink);
                        moreTd.append(moreWrap);
                        segMoreNodes.push(moreTd[0]);
                        moreNodes.push(moreTd[0]);
                    }

                    td.addClass('fc-limited').after($(segMoreNodes)); // hide original <td> and inject replacements
                    limitedNodes.push(td[0]);
                }
            }

            emptyCellsUntil(this.colCnt); // finish off the level
            rowStruct.moreEls = $(moreNodes); // for easy undoing later
            rowStruct.limitedEls = $(limitedNodes); // for easy undoing later
        }
    },


    // Reveals all levels and removes all "more"-related elements for a grid's row.
    // `row` is a row number.
    unlimitRow: function(row) {
        var rowStruct = this.rowStructs[row];

        if (rowStruct.moreEls) {
            rowStruct.moreEls.remove();
            rowStruct.moreEls = null;
        }

        if (rowStruct.limitedEls) {
            rowStruct.limitedEls.removeClass('fc-limited');
            rowStruct.limitedEls = null;
        }
    },


    // Renders an <a> element that represents hidden event element for a cell.
    // Responsible for attaching click handler as well.
    renderMoreLink: function(cell, hiddenSegs) {
        var _this = this;
        var view = this.view;

        return $('<a class="fc-more"/>')
            .text(
                this.getMoreLinkText(hiddenSegs.length)
            )
            .on('click', function(ev) {
                var clickOption = view.opt('eventLimitClick');
                var date = cell.start;
                var moreEl = $(this);
                var dayEl = _this.getCellDayEl(cell);
                var allSegs = _this.getCellSegs(cell);

                // rescope the segments to be within the cell's date
                var reslicedAllSegs = _this.resliceDaySegs(allSegs, date);
                var reslicedHiddenSegs = _this.resliceDaySegs(hiddenSegs, date);

                if (typeof clickOption === 'function') {
                    // the returned value can be an atomic option
                    clickOption = view.trigger('eventLimitClick', null, {
                        date: date,
                        dayEl: dayEl,
                        moreEl: moreEl,
                        segs: reslicedAllSegs,
                        hiddenSegs: reslicedHiddenSegs
                    }, ev);
                }

                if (clickOption === 'popover') {
                    _this.showSegPopover(cell, moreEl, reslicedAllSegs);
                }
                else if (typeof clickOption === 'string') { // a view name
                    view.calendar.zoomTo(date, clickOption);
                }
            });
    },


    // Reveals the popover that displays all events within a cell
    showSegPopover: function(cell, moreLink, segs) {
        var _this = this;
        var view = this.view;
        var moreWrap = moreLink.parent(); // the <div> wrapper around the <a>
        var topEl; // the element we want to match the top coordinate of
        var options;

        if (this.rowCnt == 1) {
            topEl = view.el; // will cause the popover to cover any sort of header
        }
        else {
            topEl = this.rowEls.eq(cell.row); // will align with top of row
        }

        options = {
            className: 'fc-more-popover',
            content: this.renderSegPopoverContent(cell, segs),
            parentEl: this.el,
            top: topEl.offset().top,
            autoHide: true, // when the user clicks elsewhere, hide the popover
            viewportConstrain: view.opt('popoverViewportConstrain'),
            hide: function() {
                // kill everything when the popover is hidden
                _this.segPopover.removeElement();
                _this.segPopover = null;
                _this.popoverSegs = null;
            }
        };

        // Determine horizontal coordinate.
        // We use the moreWrap instead of the <td> to avoid border confusion.
        if (this.isRTL) {
            options.right = moreWrap.offset().left + moreWrap.outerWidth() + 1; // +1 to be over cell border
        }
        else {
            options.left = moreWrap.offset().left - 1; // -1 to be over cell border
        }

        this.segPopover = new Popover(options);
        this.segPopover.show();
    },


    // Builds the inner DOM contents of the segment popover
    renderSegPopoverContent: function(cell, segs) {
        var view = this.view;
        var isTheme = view.opt('theme');
        var title = cell.start.format(view.opt('dayPopoverFormat'));
        var content = $(
            '<div class="fc-header ' + view.widgetHeaderClass + '">' +
                '<span class="fc-close ' +
                    (isTheme ? 'ui-icon ui-icon-closethick' : 'fc-icon fc-icon-x') +
                '"></span>' +
                '<span class="fc-title">' +
                    htmlEscape(title) +
                '</span>' +
                '<div class="fc-clear"/>' +
            '</div>' +
            '<div class="fc-body ' + view.widgetContentClass + '">' +
                '<div class="fc-event-container"></div>' +
            '</div>'
        );
        var segContainer = content.find('.fc-event-container');
        var i;

        // render each seg's `el` and only return the visible segs
        segs = this.renderFgSegEls(segs, true); // disableResizing=true
        this.popoverSegs = segs;

        for (i = 0; i < segs.length; i++) {

            // because segments in the popover are not part of a grid coordinate system, provide a hint to any
            // grids that want to do drag-n-drop about which cell it came from
            segs[i].cell = cell;

            segContainer.append(segs[i].el);
        }

        return content;
    },


    // Given the events within an array of segment objects, reslice them to be in a single day
    resliceDaySegs: function(segs, dayDate) {

        // build an array of the original events
        var events = $.map(segs, function(seg) {
            return seg.event;
        });

        var dayStart = dayDate.clone().stripTime();
        var dayEnd = dayStart.clone().add(1, 'days');
        var dayRange = { start: dayStart, end: dayEnd };

        // slice the events with a custom slicing function
        segs = this.eventsToSegs(
            events,
            function(range) {
                var seg = intersectionToSeg(range, dayRange); // undefind if no intersection
                return seg ? [ seg ] : []; // must return an array of segments
            }
        );

        // force an order because eventsToSegs doesn't guarantee one
        this.sortSegs(segs);

        return segs;
    },


    // Generates the text that should be inside a "more" link, given the number of events it represents
    getMoreLinkText: function(num) {
        var opt = this.view.opt('eventLimitText');

        if (typeof opt === 'function') {
            return opt(num);
        }
        else {
            return '+' + num + ' ' + opt;
        }
    },


    // Returns segments within a given cell.
    // If `startLevel` is specified, returns only events including and below that level. Otherwise returns all segs.
    getCellSegs: function(cell, startLevel) {
        var segMatrix = this.rowStructs[cell.row].segMatrix;
        var level = startLevel || 0;
        var segs = [];
        var seg;

        while (level < segMatrix.length) {
            seg = segMatrix[level][cell.col];
            if (seg) {
                segs.push(seg);
            }
            level++;
        }

        return segs;
    }

});



/* A component that renders one or more columns of vertical time slots
----------------------------------------------------------------------------------------------------------------------*/

var TimeGrid = Grid.extend({

    slotDuration: null, // duration of a "slot", a distinct time segment on given day, visualized by lines
    snapDuration: null, // granularity of time for dragging and selecting
    minTime: null, // Duration object that denotes the first visible time of any given day
    maxTime: null, // Duration object that denotes the exclusive visible end time of any given day
    colDates: null, // whole-day dates for each column. left to right
    labelFormat: null, // formatting string for times running along vertical axis
    labelInterval: null, // duration of how often a label should be displayed for a slot

    dayEls: null, // cells elements in the day-row background
    slatEls: null, // elements running horizontally across all columns

    slatTops: null, // an array of top positions, relative to the container. last item holds bottom of last slot

    helperEl: null, // cell skeleton element for rendering the mock event "helper"

    businessHourSegs: null,


    constructor: function() {
        Grid.apply(this, arguments); // call the super-constructor
        this.processOptions();
    },


    // Renders the time grid into `this.el`, which should already be assigned.
    // Relies on the view's colCnt. In the future, this component should probably be self-sufficient.
    renderDates: function() {
        this.el.html(this.renderHtml());
        this.dayEls = this.el.find('.fc-day');
        this.slatEls = this.el.find('.fc-slats tr');
    },


    renderBusinessHours: function() {
        var events = this.view.calendar.getBusinessHoursEvents();
        this.businessHourSegs = this.renderFill('businessHours', this.eventsToSegs(events), 'bgevent');
    },


    // Renders the basic HTML skeleton for the grid
    renderHtml: function() {
        return '' +
            '<div class="fc-bg">' +
                '<table>' +
                    this.rowHtml('slotBg') + // leverages RowRenderer, which will call slotBgCellHtml
                '</table>' +
            '</div>' +
            '<div class="fc-slats">' +
                '<table>' +
                    this.slatRowHtml() +
                '</table>' +
            '</div>';
    },


    // Renders the HTML for a vertical background cell behind the slots.
    // This method is distinct from 'bg' because we wanted a new `rowType` so the View could customize the rendering.
    slotBgCellHtml: function(cell) {
        return this.bgCellHtml(cell);
    },


    // Generates the HTML for the horizontal "slats" that run width-wise. Has a time axis on a side. Depends on RTL.
    slatRowHtml: function() {
        var view = this.view;
        var isRTL = this.isRTL;
        var html = '';
        var slotTime = moment.duration(+this.minTime); // wish there was .clone() for durations
        var slotDate; // will be on the view's first day, but we only care about its time
        var isLabeled;
        var axisHtml;

        // Calculate the time for each slot
        while (slotTime < this.maxTime) {
            slotDate = this.start.clone().time(slotTime); // after .time() will be in UTC. but that's good, avoids DST issues
            isLabeled = isInt(divideDurationByDuration(slotTime, this.labelInterval));

            axisHtml =
                '<td class="fc-axis fc-time ' + view.widgetContentClass + '" ' + view.axisStyleAttr() + '>' +
                    (isLabeled ?
                        '<span>' + // for matchCellWidths
                            htmlEscape(slotDate.format(this.labelFormat)) +
                        '</span>' :
                        ''
                        ) +
                '</td>';

            html +=
                '<tr ' + (isLabeled ? '' : 'class="fc-minor"') + '>' +
                    (!isRTL ? axisHtml : '') +
                    '<td class="' + view.widgetContentClass + '"/>' +
                    (isRTL ? axisHtml : '') +
                "</tr>";

            slotTime.add(this.slotDuration);
        }

        return html;
    },


    /* Options
    ------------------------------------------------------------------------------------------------------------------*/


    // Parses various options into properties of this object
    processOptions: function() {
        var view = this.view;
        var slotDuration = view.opt('slotDuration');
        var snapDuration = view.opt('snapDuration');
        var input;

        slotDuration = moment.duration(slotDuration);
        snapDuration = snapDuration ? moment.duration(snapDuration) : slotDuration;

        this.slotDuration = slotDuration;
        this.snapDuration = snapDuration;
        this.cellDuration = snapDuration; // for Grid system

        this.minTime = moment.duration(view.opt('minTime'));
        this.maxTime = moment.duration(view.opt('maxTime'));

        // might be an array value (for TimelineView).
        // if so, getting the most granular entry (the last one probably).
        input = view.opt('slotLabelFormat');
        if ($.isArray(input)) {
            input = input[input.length - 1];
        }

        this.labelFormat =
            input ||
            view.opt('axisFormat') || // deprecated
            view.opt('smallTimeFormat'); // the computed default

        input = view.opt('slotLabelInterval');
        this.labelInterval = input ?
            moment.duration(input) :
            this.computeLabelInterval(slotDuration);
    },


    // Computes an automatic value for slotLabelInterval
    computeLabelInterval: function(slotDuration) {
        var i;
        var labelInterval;
        var slotsPerLabel;

        // find the smallest stock label interval that results in more than one slots-per-label
        for (i = AGENDA_STOCK_SUB_DURATIONS.length - 1; i >= 0; i--) {
            labelInterval = moment.duration(AGENDA_STOCK_SUB_DURATIONS[i]);
            slotsPerLabel = divideDurationByDuration(labelInterval, slotDuration);
            if (isInt(slotsPerLabel) && slotsPerLabel > 1) {
                return labelInterval;
            }
        }

        return moment.duration(slotDuration); // fall back. clone
    },


    // Computes a default column header formatting string if `colFormat` is not explicitly defined
    computeColHeadFormat: function() {
        if (this.colCnt > 1) { // multiple days, so full single date string WON'T be in title text
            return this.view.opt('dayOfMonthFormat'); // "Sat 12/10"
        }
        else { // single day, so full single date string will probably be in title text
            return 'dddd'; // "Saturday"
        }
    },


    // Computes a default event time formatting string if `timeFormat` is not explicitly defined
    computeEventTimeFormat: function() {
        return this.view.opt('noMeridiemTimeFormat'); // like "6:30" (no AM/PM)
    },


    // Computes a default `displayEventEnd` value if one is not expliclty defined
    computeDisplayEventEnd: function() {
        return true;
    },


    /* Cell System
    ------------------------------------------------------------------------------------------------------------------*/


    rangeUpdated: function() {
        var view = this.view;
        var colDates = [];
        var date;

        date = this.start.clone();
        while (date.isBefore(this.end)) {
            colDates.push(date.clone());
            date.add(1, 'day');
            date = view.skipHiddenDays(date);
        }

        if (this.isRTL) {
            colDates.reverse();
        }

        this.colDates = colDates;
        this.colCnt = colDates.length;
        this.rowCnt = Math.ceil((this.maxTime - this.minTime) / this.snapDuration); // # of vertical snaps
    },


    // Given a cell object, generates its start date. Returns a reference-free copy.
    computeCellDate: function(cell) {
        var date = this.colDates[cell.col];
        var time = this.computeSnapTime(cell.row);

        date = this.view.calendar.rezoneDate(date); // give it a 00:00 time
        date.time(time);

        return date;
    },


    // Retrieves the element representing the given column
    getColEl: function(col) {
        return this.dayEls.eq(col);
    },


    /* Dates
    ------------------------------------------------------------------------------------------------------------------*/


    // Given a row number of the grid, representing a "snap", returns a time (Duration) from its start-of-day
    computeSnapTime: function(row) {
        return moment.duration(this.minTime + this.snapDuration * row);
    },


    // Slices up a date range by column into an array of segments
    rangeToSegs: function(range) {
        var colCnt = this.colCnt;
        var segs = [];
        var seg;
        var col;
        var colDate;
        var colRange;

        // normalize :(
        range = {
            start: range.start.clone().stripZone(),
            end: range.end.clone().stripZone()
        };

        for (col = 0; col < colCnt; col++) {
            colDate = this.colDates[col]; // will be ambig time/timezone
            colRange = {
                start: colDate.clone().time(this.minTime),
                end: colDate.clone().time(this.maxTime)
            };
            seg = intersectionToSeg(range, colRange); // both will be ambig timezone
            if (seg) {
                seg.col = col;
                segs.push(seg);
            }
        }

        return segs;
    },


    /* Coordinates
    ------------------------------------------------------------------------------------------------------------------*/


    updateSize: function(isResize) { // NOT a standard Grid method
        this.computeSlatTops();

        if (isResize) {
            this.updateSegVerticals();
        }
    },


    // Computes the top/bottom coordinates of each "snap" rows
    computeRowCoords: function() {
        var originTop = this.el.offset().top;
        var items = [];
        var i;
        var item;

        for (i = 0; i < this.rowCnt; i++) {
            item = {
                top: originTop + this.computeTimeTop(this.computeSnapTime(i))
            };
            if (i > 0) {
                items[i - 1].bottom = item.top;
            }
            items.push(item);
        }
        item.bottom = item.top + this.computeTimeTop(this.computeSnapTime(i));

        return items;
    },


    // Computes the top coordinate, relative to the bounds of the grid, of the given date.
    // A `startOfDayDate` must be given for avoiding ambiguity over how to treat midnight.
    computeDateTop: function(date, startOfDayDate) {
        return this.computeTimeTop(
            moment.duration(
                date.clone().stripZone() - startOfDayDate.clone().stripTime()
            )
        );
    },


    // Computes the top coordinate, relative to the bounds of the grid, of the given time (a Duration).
    computeTimeTop: function(time) {
        var slatCoverage = (time - this.minTime) / this.slotDuration; // floating-point value of # of slots covered
        var slatIndex;
        var slatRemainder;
        var slatTop;
        var slatBottom;

        // constrain. because minTime/maxTime might be customized
        slatCoverage = Math.max(0, slatCoverage);
        slatCoverage = Math.min(this.slatEls.length, slatCoverage);

        slatIndex = Math.floor(slatCoverage); // an integer index of the furthest whole slot
        slatRemainder = slatCoverage - slatIndex;
        slatTop = this.slatTops[slatIndex]; // the top position of the furthest whole slot

        if (slatRemainder) { // time spans part-way into the slot
            slatBottom = this.slatTops[slatIndex + 1];
            return slatTop + (slatBottom - slatTop) * slatRemainder; // part-way between slots
        }
        else {
            return slatTop;
        }
    },


    // Queries each `slatEl` for its position relative to the grid's container and stores it in `slatTops`.
    // Includes the the bottom of the last slat as the last item in the array.
    computeSlatTops: function() {
        var tops = [];
        var top;

        this.slatEls.each(function(i, node) {
            top = $(node).position().top;
            tops.push(top);
        });

        tops.push(top + this.slatEls.last().outerHeight()); // bottom of the last slat

        this.slatTops = tops;
    },


    /* Event Drag Visualization
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of an event being dragged over the specified date(s).
    // dropLocation's end might be null, as well as `seg`. See Grid::renderDrag for more info.
    // A returned value of `true` signals that a mock "helper" event has been rendered.
    renderDrag: function(dropLocation, seg) {

        if (seg) { // if there is event information for this drag, render a helper event
            this.renderRangeHelper(dropLocation, seg);
            this.applyDragOpacity(this.helperEl);

            return true; // signal that a helper has been rendered
        }
        else {
            // otherwise, just render a highlight
            this.renderHighlight(this.eventRangeToSegs(dropLocation));
        }
    },


    // Unrenders any visual indication of an event being dragged
    unrenderDrag: function() {
        this.unrenderHelper();
        this.unrenderHighlight();
    },


    /* Event Resize Visualization
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of an event being resized
    renderEventResize: function(range, seg) {
        this.renderRangeHelper(range, seg);
    },


    // Unrenders any visual indication of an event being resized
    unrenderEventResize: function() {
        this.unrenderHelper();
    },


    /* Event Helper
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a mock "helper" event. `sourceSeg` is the original segment object and might be null (an external drag)
    renderHelper: function(event, sourceSeg) {
        var segs = this.eventsToSegs([ event ]);
        var tableEl;
        var i, seg;
        var sourceEl;

        segs = this.renderFgSegEls(segs); // assigns each seg's el and returns a subset of segs that were rendered
        tableEl = this.renderSegTable(segs);

        // Try to make the segment that is in the same row as sourceSeg look the same
        for (i = 0; i < segs.length; i++) {
            seg = segs[i];
            if (sourceSeg && sourceSeg.col === seg.col) {
                sourceEl = sourceSeg.el;
                seg.el.css({
                    left: sourceEl.css('left'),
                    right: sourceEl.css('right'),
                    'margin-left': sourceEl.css('margin-left'),
                    'margin-right': sourceEl.css('margin-right')
                });
            }
        }

        this.helperEl = $('<div class="fc-helper-skeleton"/>')
            .append(tableEl)
                .appendTo(this.el);
    },


    // Unrenders any mock helper event
    unrenderHelper: function() {
        if (this.helperEl) {
            this.helperEl.remove();
            this.helperEl = null;
        }
    },


    /* Selection
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of a selection. Overrides the default, which was to simply render a highlight.
    renderSelection: function(range) {
        if (this.view.opt('selectHelper')) { // this setting signals that a mock helper event should be rendered
            this.renderRangeHelper(range);
        }
        else {
            this.renderHighlight(this.selectionRangeToSegs(range));
        }
    },


    // Unrenders any visual indication of a selection
    unrenderSelection: function() {
        this.unrenderHelper();
        this.unrenderHighlight();
    },


    /* Fill System (highlight, background events, business hours)
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a set of rectangles over the given time segments.
    // Only returns segments that successfully rendered.
    renderFill: function(type, segs, className) {
        var segCols;
        var skeletonEl;
        var trEl;
        var col, colSegs;
        var tdEl;
        var containerEl;
        var dayDate;
        var i, seg;

        if (segs.length) {

            segs = this.renderFillSegEls(type, segs); // assignes `.el` to each seg. returns successfully rendered segs
            segCols = this.groupSegCols(segs); // group into sub-arrays, and assigns 'col' to each seg

            className = className || type.toLowerCase();
            skeletonEl = $(
                '<div class="fc-' + className + '-skeleton">' +
                    '<table><tr/></table>' +
                '</div>'
            );
            trEl = skeletonEl.find('tr');

            for (col = 0; col < segCols.length; col++) {
                colSegs = segCols[col];
                tdEl = $('<td/>').appendTo(trEl);

                if (colSegs.length) {
                    containerEl = $('<div class="fc-' + className + '-container"/>').appendTo(tdEl);
                    dayDate = this.colDates[col];

                    for (i = 0; i < colSegs.length; i++) {
                        seg = colSegs[i];
                        containerEl.append(
                            seg.el.css({
                                top: this.computeDateTop(seg.start, dayDate),
                                bottom: -this.computeDateTop(seg.end, dayDate) // the y position of the bottom edge
                            })
                        );
                    }
                }
            }

            this.bookendCells(trEl, type);

            this.el.append(skeletonEl);
            this.elsByFill[type] = skeletonEl;
        }

        return segs;
    }

});



/* Event-rendering methods for the TimeGrid class
----------------------------------------------------------------------------------------------------------------------*/

TimeGrid.mixin({

    eventSkeletonEl: null, // has cells with event-containers, which contain absolutely positioned event elements


    // Renders the given foreground event segments onto the grid
    renderFgSegs: function(segs) {
        segs = this.renderFgSegEls(segs); // returns a subset of the segs. segs that were actually rendered

        this.el.append(
            this.eventSkeletonEl = $('<div class="fc-content-skeleton"/>')
                .append(this.renderSegTable(segs))
        );

        return segs; // return only the segs that were actually rendered
    },


    // Unrenders all currently rendered foreground event segments
    unrenderFgSegs: function(segs) {
        if (this.eventSkeletonEl) {
            this.eventSkeletonEl.remove();
            this.eventSkeletonEl = null;
        }
    },


    // Renders and returns the <table> portion of the event-skeleton.
    // Returns an object with properties 'tbodyEl' and 'segs'.
    renderSegTable: function(segs) {
        var tableEl = $('<table><tr/></table>');
        var trEl = tableEl.find('tr');
        var segCols;
        var i, seg;
        var col, colSegs;
        var containerEl;

        segCols = this.groupSegCols(segs); // group into sub-arrays, and assigns 'col' to each seg

        this.computeSegVerticals(segs); // compute and assign top/bottom

        for (col = 0; col < segCols.length; col++) { // iterate each column grouping
            colSegs = segCols[col];
            this.placeSlotSegs(colSegs); // compute horizontal coordinates, z-index's, and reorder the array

            containerEl = $('<div class="fc-event-container"/>');

            // assign positioning CSS and insert into container
            for (i = 0; i < colSegs.length; i++) {
                seg = colSegs[i];
                seg.el.css(this.generateSegPositionCss(seg));

                // if the height is short, add a className for alternate styling
                if (seg.bottom - seg.top < 30) {
                    seg.el.addClass('fc-short');
                }

                containerEl.append(seg.el);
            }

            trEl.append($('<td/>').append(containerEl));
        }

        this.bookendCells(trEl, 'eventSkeleton');

        return tableEl;
    },


    // Given an array of segments that are all in the same column, sets the backwardCoord and forwardCoord on each.
    // NOTE: Also reorders the given array by date!
    placeSlotSegs: function(segs) {
        var levels;
        var level0;
        var i;

        this.sortSegs(segs); // order by date
        levels = buildSlotSegLevels(segs);
        computeForwardSlotSegs(levels);

        if ((level0 = levels[0])) {

            for (i = 0; i < level0.length; i++) {
                computeSlotSegPressures(level0[i]);
            }

            for (i = 0; i < level0.length; i++) {
                this.computeSlotSegCoords(level0[i], 0, 0);
            }
        }
    },


    // Calculate seg.forwardCoord and seg.backwardCoord for the segment, where both values range
    // from 0 to 1. If the calendar is left-to-right, the seg.backwardCoord maps to "left" and
    // seg.forwardCoord maps to "right" (via percentage). Vice-versa if the calendar is right-to-left.
    //
    // The segment might be part of a "series", which means consecutive segments with the same pressure
    // who's width is unknown until an edge has been hit. `seriesBackwardPressure` is the number of
    // segments behind this one in the current series, and `seriesBackwardCoord` is the starting
    // coordinate of the first segment in the series.
    computeSlotSegCoords: function(seg, seriesBackwardPressure, seriesBackwardCoord) {
        var forwardSegs = seg.forwardSegs;
        var i;

        if (seg.forwardCoord === undefined) { // not already computed

            if (!forwardSegs.length) {

                // if there are no forward segments, this segment should butt up against the edge
                seg.forwardCoord = 1;
            }
            else {

                // sort highest pressure first
                this.sortForwardSlotSegs(forwardSegs);

                // this segment's forwardCoord will be calculated from the backwardCoord of the
                // highest-pressure forward segment.
                this.computeSlotSegCoords(forwardSegs[0], seriesBackwardPressure + 1, seriesBackwardCoord);
                seg.forwardCoord = forwardSegs[0].backwardCoord;
            }

            // calculate the backwardCoord from the forwardCoord. consider the series
            seg.backwardCoord = seg.forwardCoord -
                (seg.forwardCoord - seriesBackwardCoord) / // available width for series
                (seriesBackwardPressure + 1); // # of segments in the series

            // use this segment's coordinates to computed the coordinates of the less-pressurized
            // forward segments
            for (i=0; i<forwardSegs.length; i++) {
                this.computeSlotSegCoords(forwardSegs[i], 0, seg.forwardCoord);
            }
        }
    },


    // Refreshes the CSS top/bottom coordinates for each segment element. Probably after a window resize/zoom.
    // Repositions business hours segs too, so not just for events. Maybe shouldn't be here.
    updateSegVerticals: function() {
        var allSegs = (this.segs || []).concat(this.businessHourSegs || []);
        var i;

        this.computeSegVerticals(allSegs);

        for (i = 0; i < allSegs.length; i++) {
            allSegs[i].el.css(
                this.generateSegVerticalCss(allSegs[i])
            );
        }
    },


    // For each segment in an array, computes and assigns its top and bottom properties
    computeSegVerticals: function(segs) {
        var i, seg;

        for (i = 0; i < segs.length; i++) {
            seg = segs[i];
            seg.top = this.computeDateTop(seg.start, seg.start);
            seg.bottom = this.computeDateTop(seg.end, seg.start);
        }
    },


    // Renders the HTML for a single event segment's default rendering
    fgSegHtml: function(seg, disableResizing) {
        var view = this.view;
        var event = seg.event;
        var isDraggable = view.isEventDraggable(event);
        var isResizableFromStart = !disableResizing && seg.isStart && view.isEventResizableFromStart(event);
        var isResizableFromEnd = !disableResizing && seg.isEnd && view.isEventResizableFromEnd(event);
        var classes = this.getSegClasses(seg, isDraggable, isResizableFromStart || isResizableFromEnd);
        var skinCss = cssToStr(this.getEventSkinCss(event));
        var timeText;
        var fullTimeText; // more verbose time text. for the print stylesheet
        var startTimeText; // just the start time text

        classes.unshift('fc-time-grid-event', 'fc-v-event');

        if (view.isMultiDayEvent(event)) { // if the event appears to span more than one day...
            // Don't display time text on segments that run entirely through a day.
            // That would appear as midnight-midnight and would look dumb.
            // Otherwise, display the time text for the *segment's* times (like 6pm-midnight or midnight-10am)
            if (seg.isStart || seg.isEnd) {
                timeText = this.getEventTimeText(seg);
                fullTimeText = this.getEventTimeText(seg, 'LT');
                startTimeText = this.getEventTimeText(seg, null, false); // displayEnd=false
            }
        } else {
            // Display the normal time text for the *event's* times
            timeText = this.getEventTimeText(event);
            fullTimeText = this.getEventTimeText(event, 'LT');
            startTimeText = this.getEventTimeText(event, null, false); // displayEnd=false
        }

        return '<a class="' + classes.join(' ') + '"' +
            (event.url ?
                ' href="' + htmlEscape(event.url) + '"' :
                ''
                ) +
            (skinCss ?
                ' style="' + skinCss + '"' :
                ''
                ) +
            '>' +
                '<div class="fc-content">' +
                    (timeText ?
                        '<div class="fc-time"' +
                        ' data-start="' + htmlEscape(startTimeText) + '"' +
                        ' data-full="' + htmlEscape(fullTimeText) + '"' +
                        '>' +
                            '<span>' + htmlEscape(timeText) + '</span>' +
                        '</div>' :
                        ''
                        ) +
                    (event.title ?
                        '<div class="fc-title">' +
                            htmlEscape(event.title) +
                        '</div>' :
                        ''
                        ) +
                '</div>' +
                '<div class="fc-bg"/>' +
                /* TODO: write CSS for this
                (isResizableFromStart ?
                    '<div class="fc-resizer fc-start-resizer" />' :
                    ''
                    ) +
                */
                (isResizableFromEnd ?
                    '<div class="fc-resizer fc-end-resizer" />' :
                    ''
                    ) +
            '</a>';
    },


    // Generates an object with CSS properties/values that should be applied to an event segment element.
    // Contains important positioning-related properties that should be applied to any event element, customized or not.
    generateSegPositionCss: function(seg) {
        var shouldOverlap = this.view.opt('slotEventOverlap');
        var backwardCoord = seg.backwardCoord; // the left side if LTR. the right side if RTL. floating-point
        var forwardCoord = seg.forwardCoord; // the right side if LTR. the left side if RTL. floating-point
        var props = this.generateSegVerticalCss(seg); // get top/bottom first
        var left; // amount of space from left edge, a fraction of the total width
        var right; // amount of space from right edge, a fraction of the total width

        if (shouldOverlap) {
            // double the width, but don't go beyond the maximum forward coordinate (1.0)
            forwardCoord = Math.min(1, backwardCoord + (forwardCoord - backwardCoord) * 2);
        }

        if (this.isRTL) {
            left = 1 - forwardCoord;
            right = backwardCoord;
        }
        else {
            left = backwardCoord;
            right = 1 - forwardCoord;
        }

        props.zIndex = seg.level + 1; // convert from 0-base to 1-based
        props.left = left * 100 + '%';
        props.right = right * 100 + '%';

        if (shouldOverlap && seg.forwardPressure) {
            // add padding to the edge so that forward stacked events don't cover the resizer's icon
            props[this.isRTL ? 'marginLeft' : 'marginRight'] = 10 * 2; // 10 is a guesstimate of the icon's width
        }

        return props;
    },


    // Generates an object with CSS properties for the top/bottom coordinates of a segment element
    generateSegVerticalCss: function(seg) {
        return {
            top: seg.top,
            bottom: -seg.bottom // flipped because needs to be space beyond bottom edge of event container
        };
    },


    // Given a flat array of segments, return an array of sub-arrays, grouped by each segment's col
    groupSegCols: function(segs) {
        var segCols = [];
        var i;

        for (i = 0; i < this.colCnt; i++) {
            segCols.push([]);
        }

        for (i = 0; i < segs.length; i++) {
            segCols[segs[i].col].push(segs[i]);
        }

        return segCols;
    },


    sortForwardSlotSegs: function(forwardSegs) {
        forwardSegs.sort(proxy(this, 'compareForwardSlotSegs'));
    },


    // A cmp function for determining which forward segment to rely on more when computing coordinates.
    compareForwardSlotSegs: function(seg1, seg2) {
        // put higher-pressure first
        return seg2.forwardPressure - seg1.forwardPressure ||
            // put segments that are closer to initial edge first (and favor ones with no coords yet)
            (seg1.backwardCoord || 0) - (seg2.backwardCoord || 0) ||
            // do normal sorting...
            this.compareSegs(seg1, seg2);
    }

});


// Builds an array of segments "levels". The first level will be the leftmost tier of segments if the calendar is
// left-to-right, or the rightmost if the calendar is right-to-left. Assumes the segments are already ordered by date.
function buildSlotSegLevels(segs) {
    var levels = [];
    var i, seg;
    var j;

    for (i=0; i<segs.length; i++) {
        seg = segs[i];

        // go through all the levels and stop on the first level where there are no collisions
        for (j=0; j<levels.length; j++) {
            if (!computeSlotSegCollisions(seg, levels[j]).length) {
                break;
            }
        }

        seg.level = j;

        (levels[j] || (levels[j] = [])).push(seg);
    }

    return levels;
}


// For every segment, figure out the other segments that are in subsequent
// levels that also occupy the same vertical space. Accumulate in seg.forwardSegs
function computeForwardSlotSegs(levels) {
    var i, level;
    var j, seg;
    var k;

    for (i=0; i<levels.length; i++) {
        level = levels[i];

        for (j=0; j<level.length; j++) {
            seg = level[j];

            seg.forwardSegs = [];
            for (k=i+1; k<levels.length; k++) {
                computeSlotSegCollisions(seg, levels[k], seg.forwardSegs);
            }
        }
    }
}


// Figure out which path forward (via seg.forwardSegs) results in the longest path until
// the furthest edge is reached. The number of segments in this path will be seg.forwardPressure
function computeSlotSegPressures(seg) {
    var forwardSegs = seg.forwardSegs;
    var forwardPressure = 0;
    var i, forwardSeg;

    if (seg.forwardPressure === undefined) { // not already computed

        for (i=0; i<forwardSegs.length; i++) {
            forwardSeg = forwardSegs[i];

            // figure out the child's maximum forward path
            computeSlotSegPressures(forwardSeg);

            // either use the existing maximum, or use the child's forward pressure
            // plus one (for the forwardSeg itself)
            forwardPressure = Math.max(
                forwardPressure,
                1 + forwardSeg.forwardPressure
            );
        }

        seg.forwardPressure = forwardPressure;
    }
}


// Find all the segments in `otherSegs` that vertically collide with `seg`.
// Append into an optionally-supplied `results` array and return.
function computeSlotSegCollisions(seg, otherSegs, results) {
    results = results || [];

    for (var i=0; i<otherSegs.length; i++) {
        if (isSlotSegCollision(seg, otherSegs[i])) {
            results.push(otherSegs[i]);
        }
    }

    return results;
}


// Do these segments occupy the same vertical space?
function isSlotSegCollision(seg1, seg2) {
    return seg1.bottom > seg2.top && seg1.top < seg2.bottom;
}



/* An abstract class from which other views inherit from
----------------------------------------------------------------------------------------------------------------------*/

var View = fc.View = Class.extend({

    type: null, // subclass' view name (string)
    name: null, // deprecated. use `type` instead
    title: null, // the text that will be displayed in the header's title

    calendar: null, // owner Calendar object
    options: null, // hash containing all options. already merged with view-specific-options
    coordMap: null, // a CoordMap object for converting pixel regions to dates
    el: null, // the view's containing element. set by Calendar

    displaying: null, // a promise representing the state of rendering. null if no render requested
    isSkeletonRendered: false,
    isEventsRendered: false,

    // range the view is actually displaying (moments)
    start: null,
    end: null, // exclusive

    // range the view is formally responsible for (moments)
    // may be different from start/end. for example, a month view might have 1st-31st, excluding padded dates
    intervalStart: null,
    intervalEnd: null, // exclusive
    intervalDuration: null,
    intervalUnit: null, // name of largest unit being displayed, like "month" or "week"

    isRTL: false,
    isSelected: false, // boolean whether a range of time is user-selected or not

    eventOrderSpecs: null, // criteria for ordering events when they have same date/time

    // subclasses can optionally use a scroll container
    scrollerEl: null, // the element that will most likely scroll when content is too tall
    scrollTop: null, // cached vertical scroll value

    // classNames styled by jqui themes
    widgetHeaderClass: null,
    widgetContentClass: null,
    highlightStateClass: null,

    // for date utils, computed from options
    nextDayThreshold: null,
    isHiddenDayHash: null,

    // document handlers, bound to `this` object
    documentMousedownProxy: null, // TODO: doesn't work with touch


    constructor: function(calendar, type, options, intervalDuration) {

        this.calendar = calendar;
        this.type = this.name = type; // .name is deprecated
        this.options = options;
        this.intervalDuration = intervalDuration || moment.duration(1, 'day');

        this.nextDayThreshold = moment.duration(this.opt('nextDayThreshold'));
        this.initThemingProps();
        this.initHiddenDays();
        this.isRTL = this.opt('isRTL');

        this.eventOrderSpecs = parseFieldSpecs(this.opt('eventOrder'));

        this.documentMousedownProxy = proxy(this, 'documentMousedown');

        this.initialize();
    },


    // A good place for subclasses to initialize member variables
    initialize: function() {
        // subclasses can implement
    },


    // Retrieves an option with the given name
    opt: function(name) {
        return this.options[name];
    },


    // Triggers handlers that are view-related. Modifies args before passing to calendar.
    trigger: function(name, thisObj) { // arguments beyond thisObj are passed along
        var calendar = this.calendar;

        return calendar.trigger.apply(
            calendar,
            [name, thisObj || this].concat(
                Array.prototype.slice.call(arguments, 2), // arguments beyond thisObj
                [ this ] // always make the last argument a reference to the view. TODO: deprecate
            )
        );
    },


    /* Dates
    ------------------------------------------------------------------------------------------------------------------*/


    // Updates all internal dates to center around the given current date
    setDate: function(date) {
        this.setRange(this.computeRange(date));
    },


    // Updates all internal dates for displaying the given range.
    // Expects all values to be normalized (like what computeRange does).
    setRange: function(range) {
        $.extend(this, range);
        this.updateTitle();
    },


    // Given a single current date, produce information about what range to display.
    // Subclasses can override. Must return all properties.
    computeRange: function(date) {
        var intervalUnit = computeIntervalUnit(this.intervalDuration);
        var intervalStart = date.clone().startOf(intervalUnit);
        var intervalEnd = intervalStart.clone().add(this.intervalDuration);
        var start, end;

        // normalize the range's time-ambiguity
        if (/year|month|week|day/.test(intervalUnit)) { // whole-days?
            intervalStart.stripTime();
            intervalEnd.stripTime();
        }
        else { // needs to have a time?
            if (!intervalStart.hasTime()) {
                intervalStart = this.calendar.rezoneDate(intervalStart); // convert to current timezone, with 00:00
            }
            if (!intervalEnd.hasTime()) {
                intervalEnd = this.calendar.rezoneDate(intervalEnd); // convert to current timezone, with 00:00
            }
        }

        start = intervalStart.clone();
        start = this.skipHiddenDays(start);
        end = intervalEnd.clone();
        end = this.skipHiddenDays(end, -1, true); // exclusively move backwards

        return {
            intervalUnit: intervalUnit,
            intervalStart: intervalStart,
            intervalEnd: intervalEnd,
            start: start,
            end: end
        };
    },


    // Computes the new date when the user hits the prev button, given the current date
    computePrevDate: function(date) {
        return this.massageCurrentDate(
            date.clone().startOf(this.intervalUnit).subtract(this.intervalDuration), -1
        );
    },


    // Computes the new date when the user hits the next button, given the current date
    computeNextDate: function(date) {
        return this.massageCurrentDate(
            date.clone().startOf(this.intervalUnit).add(this.intervalDuration)
        );
    },


    // Given an arbitrarily calculated current date of the calendar, returns a date that is ensured to be completely
    // visible. `direction` is optional and indicates which direction the current date was being
    // incremented or decremented (1 or -1).
    massageCurrentDate: function(date, direction) {
        if (this.intervalDuration.as('days') <= 1) { // if the view displays a single day or smaller
            if (this.isHiddenDay(date)) {
                date = this.skipHiddenDays(date, direction);
                date.startOf('day');
            }
        }

        return date;
    },


    /* Title and Date Formatting
    ------------------------------------------------------------------------------------------------------------------*/


    // Sets the view's title property to the most updated computed value
    updateTitle: function() {
        this.title = this.computeTitle();
    },


    // Computes what the title at the top of the calendar should be for this view
    computeTitle: function() {
        return this.formatRange(
            { start: this.intervalStart, end: this.intervalEnd },
            this.opt('titleFormat') || this.computeTitleFormat(),
            this.opt('titleRangeSeparator')
        );
    },


    // Generates the format string that should be used to generate the title for the current date range.
    // Attempts to compute the most appropriate format if not explicitly specified with `titleFormat`.
    computeTitleFormat: function() {
        if (this.intervalUnit == 'year') {
            return 'YYYY';
        }
        else if (this.intervalUnit == 'month') {
            return this.opt('monthYearFormat'); // like "September 2014"
        }
        else if (this.intervalDuration.as('days') > 1) {
            return 'll'; // multi-day range. shorter, like "Sep 9 - 10 2014"
        }
        else {
            return 'LL'; // one day. longer, like "September 9 2014"
        }
    },


    // Utility for formatting a range. Accepts a range object, formatting string, and optional separator.
    // Displays all-day ranges naturally, with an inclusive end. Takes the current isRTL into account.
    formatRange: function(range, formatStr, separator) {
        var end = range.end;

        if (!end.hasTime()) { // all-day?
            end = end.clone().subtract(1); // convert to inclusive. last ms of previous day
        }

        return formatRange(range.start, end, formatStr, separator, this.opt('isRTL'));
    },


    /* Rendering
    ------------------------------------------------------------------------------------------------------------------*/


    // Sets the container element that the view should render inside of.
    // Does other DOM-related initializations.
    setElement: function(el) {
        this.el = el;
        this.bindGlobalHandlers();
    },


    // Removes the view's container element from the DOM, clearing any content beforehand.
    // Undoes any other DOM-related attachments.
    removeElement: function() {
        this.clear(); // clears all content

        // clean up the skeleton
        if (this.isSkeletonRendered) {
            this.unrenderSkeleton();
            this.isSkeletonRendered = false;
        }

        this.unbindGlobalHandlers();

        this.el.remove();

        // NOTE: don't null-out this.el in case the View was destroyed within an API callback.
        // We don't null-out the View's other jQuery element references upon destroy,
        //  so we shouldn't kill this.el either.
    },


    // Does everything necessary to display the view centered around the given date.
    // Does every type of rendering EXCEPT rendering events.
    // Is asychronous and returns a promise.
    display: function(date) {
        var _this = this;
        var scrollState = null;

        if (this.displaying) {
            scrollState = this.queryScroll();
        }

        return this.clear().then(function() { // clear the content first (async)
            return (
                _this.displaying =
                    $.when(_this.displayView(date)) // displayView might return a promise
                        .then(function() {
                            _this.forceScroll(_this.computeInitialScroll(scrollState));
                            _this.triggerRender();
                        })
            );
        });
    },


    // Does everything necessary to clear the content of the view.
    // Clears dates and events. Does not clear the skeleton.
    // Is asychronous and returns a promise.
    clear: function() {
        var _this = this;
        var displaying = this.displaying;

        if (displaying) { // previously displayed, or in the process of being displayed?
            return displaying.then(function() { // wait for the display to finish
                _this.displaying = null;
                _this.clearEvents();
                return _this.clearView(); // might return a promise. chain it
            });
        }
        else {
            return $.when(); // an immediately-resolved promise
        }
    },


    // Displays the view's non-event content, such as date-related content or anything required by events.
    // Renders the view's non-content skeleton if necessary.
    // Can be asynchronous and return a promise.
    displayView: function(date) {
        if (!this.isSkeletonRendered) {
            this.renderSkeleton();
            this.isSkeletonRendered = true;
        }
        this.setDate(date);
        if (this.render) {
            this.render(); // TODO: deprecate
        }
        this.renderDates();
        this.updateSize();
        this.renderBusinessHours(); // might need coordinates, so should go after updateSize()
    },


    // Unrenders the view content that was rendered in displayView.
    // Can be asynchronous and return a promise.
    clearView: function() {
        this.unselect();
        this.triggerUnrender();
        this.unrenderBusinessHours();
        this.unrenderDates();
        if (this.destroy) {
            this.destroy(); // TODO: deprecate
        }
    },


    // Renders the basic structure of the view before any content is rendered
    renderSkeleton: function() {
        // subclasses should implement
    },


    // Unrenders the basic structure of the view
    unrenderSkeleton: function() {
        // subclasses should implement
    },


    // Renders the view's date-related content (like cells that represent days/times).
    // Assumes setRange has already been called and the skeleton has already been rendered.
    renderDates: function() {
        // subclasses should implement
    },


    // Unrenders the view's date-related content
    unrenderDates: function() {
        // subclasses should override
    },


    // Renders business-hours onto the view. Assumes updateSize has already been called.
    renderBusinessHours: function() {
        // subclasses should implement
    },


    // Unrenders previously-rendered business-hours
    unrenderBusinessHours: function() {
        // subclasses should implement
    },


    // Signals that the view's content has been rendered
    triggerRender: function() {
        this.trigger('viewRender', this, this, this.el);
    },


    // Signals that the view's content is about to be unrendered
    triggerUnrender: function() {
        this.trigger('viewDestroy', this, this, this.el);
    },


    // Binds DOM handlers to elements that reside outside the view container, such as the document
    bindGlobalHandlers: function() {
        $(document).on('mousedown', this.documentMousedownProxy);
    },


    // Unbinds DOM handlers from elements that reside outside the view container
    unbindGlobalHandlers: function() {
        $(document).off('mousedown', this.documentMousedownProxy);
    },


    // Initializes internal variables related to theming
    initThemingProps: function() {
        var tm = this.opt('theme') ? 'ui' : 'fc';

        this.widgetHeaderClass = tm + '-widget-header';
        this.widgetContentClass = tm + '-widget-content';
        this.highlightStateClass = tm + '-state-highlight';
    },


    /* Dimensions
    ------------------------------------------------------------------------------------------------------------------*/


    // Refreshes anything dependant upon sizing of the container element of the grid
    updateSize: function(isResize) {
        var scrollState;

        if (isResize) {
            scrollState = this.queryScroll();
        }

        this.updateHeight(isResize);
        this.updateWidth(isResize);

        if (isResize) {
            this.setScroll(scrollState);
        }
    },


    // Refreshes the horizontal dimensions of the calendar
    updateWidth: function(isResize) {
        // subclasses should implement
    },


    // Refreshes the vertical dimensions of the calendar
    updateHeight: function(isResize) {
        var calendar = this.calendar; // we poll the calendar for height information

        this.setHeight(
            calendar.getSuggestedViewHeight(),
            calendar.isHeightAuto()
        );
    },


    // Updates the vertical dimensions of the calendar to the specified height.
    // if `isAuto` is set to true, height becomes merely a suggestion and the view should use its "natural" height.
    setHeight: function(height, isAuto) {
        // subclasses should implement
    },


    /* Scroller
    ------------------------------------------------------------------------------------------------------------------*/


    // Given the total height of the view, return the number of pixels that should be used for the scroller.
    // Utility for subclasses.
    computeScrollerHeight: function(totalHeight) {
        var scrollerEl = this.scrollerEl;
        var both;
        var otherHeight; // cumulative height of everything that is not the scrollerEl in the view (header+borders)

        both = this.el.add(scrollerEl);

        // fuckin IE8/9/10/11 sometimes returns 0 for dimensions. this weird hack was the only thing that worked
        both.css({
            position: 'relative', // cause a reflow, which will force fresh dimension recalculation
            left: -1 // ensure reflow in case the el was already relative. negative is less likely to cause new scroll
        });
        otherHeight = this.el.outerHeight() - scrollerEl.height(); // grab the dimensions
        both.css({ position: '', left: '' }); // undo hack

        return totalHeight - otherHeight;
    },


    // Computes the initial pre-configured scroll state prior to allowing the user to change it.
    // Given the scroll state from the previous rendering. If first time rendering, given null.
    computeInitialScroll: function(previousScrollState) {
        return 0;
    },


    // Retrieves the view's current natural scroll state. Can return an arbitrary format.
    queryScroll: function() {
        if (this.scrollerEl) {
            return this.scrollerEl.scrollTop(); // operates on scrollerEl by default
        }
    },


    // Sets the view's scroll state. Will accept the same format computeInitialScroll and queryScroll produce.
    setScroll: function(scrollState) {
        if (this.scrollerEl) {
            return this.scrollerEl.scrollTop(scrollState); // operates on scrollerEl by default
        }
    },


    // Sets the scroll state, making sure to overcome any predefined scroll value the browser has in mind
    forceScroll: function(scrollState) {
        var _this = this;

        this.setScroll(scrollState);
        setTimeout(function() {
            _this.setScroll(scrollState);
        }, 0);
    },


    /* Event Elements / Segments
    ------------------------------------------------------------------------------------------------------------------*/


    // Does everything necessary to display the given events onto the current view
    displayEvents: function(events) {
        var scrollState = this.queryScroll();

        this.clearEvents();
        this.renderEvents(events);
        this.isEventsRendered = true;
        this.setScroll(scrollState);
        this.triggerEventRender();
    },


    // Does everything necessary to clear the view's currently-rendered events
    clearEvents: function() {
        if (this.isEventsRendered) {
            this.triggerEventUnrender();
            if (this.destroyEvents) {
                this.destroyEvents(); // TODO: deprecate
            }
            this.unrenderEvents();
            this.isEventsRendered = false;
        }
    },


    // Renders the events onto the view.
    renderEvents: function(events) {
        // subclasses should implement
    },


    // Removes event elements from the view.
    unrenderEvents: function() {
        // subclasses should implement
    },


    // Signals that all events have been rendered
    triggerEventRender: function() {
        this.renderedEventSegEach(function(seg) {
            this.trigger('eventAfterRender', seg.event, seg.event, seg.el);
        });
        this.trigger('eventAfterAllRender');
    },


    // Signals that all event elements are about to be removed
    triggerEventUnrender: function() {
        this.renderedEventSegEach(function(seg) {
            this.trigger('eventDestroy', seg.event, seg.event, seg.el);
        });
    },


    // Given an event and the default element used for rendering, returns the element that should actually be used.
    // Basically runs events and elements through the eventRender hook.
    resolveEventEl: function(event, el) {
        var custom = this.trigger('eventRender', event, event, el);

        if (custom === false) { // means don't render at all
            el = null;
        }
        else if (custom && custom !== true) {
            el = $(custom);
        }

        return el;
    },


    // Hides all rendered event segments linked to the given event
    showEvent: function(event) {
        this.renderedEventSegEach(function(seg) {
            seg.el.css('visibility', '');
        }, event);
    },


    // Shows all rendered event segments linked to the given event
    hideEvent: function(event) {
        this.renderedEventSegEach(function(seg) {
            seg.el.css('visibility', 'hidden');
        }, event);
    },


    // Iterates through event segments that have been rendered (have an el). Goes through all by default.
    // If the optional `event` argument is specified, only iterates through segments linked to that event.
    // The `this` value of the callback function will be the view.
    renderedEventSegEach: function(func, event) {
        var segs = this.getEventSegs();
        var i;

        for (i = 0; i < segs.length; i++) {
            if (!event || segs[i].event._id === event._id) {
                if (segs[i].el) {
                    func.call(this, segs[i]);
                }
            }
        }
    },


    // Retrieves all the rendered segment objects for the view
    getEventSegs: function() {
        // subclasses must implement
        return [];
    },


    /* Event Drag-n-Drop
    ------------------------------------------------------------------------------------------------------------------*/


    // Computes if the given event is allowed to be dragged by the user
    isEventDraggable: function(event) {
        var source = event.source || {};

        return firstDefined(
            event.startEditable,
            source.startEditable,
            this.opt('eventStartEditable'),
            event.editable,
            source.editable,
            this.opt('editable')
        );
    },


    // Must be called when an event in the view is dropped onto new location.
    // `dropLocation` is an object that contains the new start/end/allDay values for the event.
    reportEventDrop: function(event, dropLocation, largeUnit, el, ev) {
        var calendar = this.calendar;
        var mutateResult = calendar.mutateEvent(event, dropLocation, largeUnit);
        var undoFunc = function() {
            mutateResult.undo();
            calendar.reportEventChange();
        };

        this.triggerEventDrop(event, mutateResult.dateDelta, undoFunc, el, ev);
        calendar.reportEventChange(); // will rerender events
    },


    // Triggers event-drop handlers that have subscribed via the API
    triggerEventDrop: function(event, dateDelta, undoFunc, el, ev) {
        this.trigger('eventDrop', el[0], event, dateDelta, undoFunc, ev, {}); // {} = jqui dummy
    },


    /* External Element Drag-n-Drop
    ------------------------------------------------------------------------------------------------------------------*/


    // Must be called when an external element, via jQuery UI, has been dropped onto the calendar.
    // `meta` is the parsed data that has been embedded into the dragging event.
    // `dropLocation` is an object that contains the new start/end/allDay values for the event.
    reportExternalDrop: function(meta, dropLocation, el, ev, ui) {
        var eventProps = meta.eventProps;
        var eventInput;
        var event;

        // Try to build an event object and render it. TODO: decouple the two
        if (eventProps) {
            eventInput = $.extend({}, eventProps, dropLocation);
            event = this.calendar.renderEvent(eventInput, meta.stick)[0]; // renderEvent returns an array
        }

        this.triggerExternalDrop(event, dropLocation, el, ev, ui);
    },


    // Triggers external-drop handlers that have subscribed via the API
    triggerExternalDrop: function(event, dropLocation, el, ev, ui) {

        // trigger 'drop' regardless of whether element represents an event
        this.trigger('drop', el[0], dropLocation.start, ev, ui);

        if (event) {
            this.trigger('eventReceive', null, event); // signal an external event landed
        }
    },


    /* Drag-n-Drop Rendering (for both events and external elements)
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of a event or external-element drag over the given drop zone.
    // If an external-element, seg will be `null`
    renderDrag: function(dropLocation, seg) {
        // subclasses must implement
    },


    // Unrenders a visual indication of an event or external-element being dragged.
    unrenderDrag: function() {
        // subclasses must implement
    },


    /* Event Resizing
    ------------------------------------------------------------------------------------------------------------------*/


    // Computes if the given event is allowed to be resized from its starting edge
    isEventResizableFromStart: function(event) {
        return this.opt('eventResizableFromStart') && this.isEventResizable(event);
    },


    // Computes if the given event is allowed to be resized from its ending edge
    isEventResizableFromEnd: function(event) {
        return this.isEventResizable(event);
    },


    // Computes if the given event is allowed to be resized by the user at all
    isEventResizable: function(event) {
        var source = event.source || {};

        return firstDefined(
            event.durationEditable,
            source.durationEditable,
            this.opt('eventDurationEditable'),
            event.editable,
            source.editable,
            this.opt('editable')
        );
    },


    // Must be called when an event in the view has been resized to a new length
    reportEventResize: function(event, resizeLocation, largeUnit, el, ev) {
        var calendar = this.calendar;
        var mutateResult = calendar.mutateEvent(event, resizeLocation, largeUnit);
        var undoFunc = function() {
            mutateResult.undo();
            calendar.reportEventChange();
        };

        this.triggerEventResize(event, mutateResult.durationDelta, undoFunc, el, ev);
        calendar.reportEventChange(); // will rerender events
    },


    // Triggers event-resize handlers that have subscribed via the API
    triggerEventResize: function(event, durationDelta, undoFunc, el, ev) {
        this.trigger('eventResize', el[0], event, durationDelta, undoFunc, ev, {}); // {} = jqui dummy
    },


    /* Selection
    ------------------------------------------------------------------------------------------------------------------*/


    // Selects a date range on the view. `start` and `end` are both Moments.
    // `ev` is the native mouse event that begin the interaction.
    select: function(range, ev) {
        this.unselect(ev);
        this.renderSelection(range);
        this.reportSelection(range, ev);
    },


    // Renders a visual indication of the selection
    renderSelection: function(range) {
        // subclasses should implement
    },


    // Called when a new selection is made. Updates internal state and triggers handlers.
    reportSelection: function(range, ev) {
        this.isSelected = true;
        this.triggerSelect(range, ev);
    },


    // Triggers handlers to 'select'
    triggerSelect: function(range, ev) {
        this.trigger('select', null, range.start, range.end, ev);
    },


    // Undoes a selection. updates in the internal state and triggers handlers.
    // `ev` is the native mouse event that began the interaction.
    unselect: function(ev) {
        if (this.isSelected) {
            this.isSelected = false;
            if (this.destroySelection) {
                this.destroySelection(); // TODO: deprecate
            }
            this.unrenderSelection();
            this.trigger('unselect', null, ev);
        }
    },


    // Unrenders a visual indication of selection
    unrenderSelection: function() {
        // subclasses should implement
    },


    // Handler for unselecting when the user clicks something and the 'unselectAuto' setting is on
    documentMousedown: function(ev) {
        var ignore;

        // is there a selection, and has the user made a proper left click?
        if (this.isSelected && this.opt('unselectAuto') && isPrimaryMouseButton(ev)) {

            // only unselect if the clicked element is not identical to or inside of an 'unselectCancel' element
            ignore = this.opt('unselectCancel');
            if (!ignore || !$(ev.target).closest(ignore).length) {
                this.unselect(ev);
            }
        }
    },


    /* Day Click
    ------------------------------------------------------------------------------------------------------------------*/


    // Triggers handlers to 'dayClick'
    triggerDayClick: function(cell, dayEl, ev) {
        this.trigger('dayClick', dayEl, cell.start, ev);
    },


    /* Date Utils
    ------------------------------------------------------------------------------------------------------------------*/


    // Initializes internal variables related to calculating hidden days-of-week
    initHiddenDays: function() {
        var hiddenDays = this.opt('hiddenDays') || []; // array of day-of-week indices that are hidden
        var isHiddenDayHash = []; // is the day-of-week hidden? (hash with day-of-week-index -> bool)
        var dayCnt = 0;
        var i;

        if (this.opt('weekends') === false) {
            hiddenDays.push(0, 6); // 0=sunday, 6=saturday
        }

        for (i = 0; i < 7; i++) {
            if (
                !(isHiddenDayHash[i] = $.inArray(i, hiddenDays) !== -1)
            ) {
                dayCnt++;
            }
        }

        if (!dayCnt) {
            throw 'invalid hiddenDays'; // all days were hidden? bad.
        }

        this.isHiddenDayHash = isHiddenDayHash;
    },


    // Is the current day hidden?
    // `day` is a day-of-week index (0-6), or a Moment
    isHiddenDay: function(day) {
        if (moment.isMoment(day)) {
            day = day.day();
        }
        return this.isHiddenDayHash[day];
    },


    // Incrementing the current day until it is no longer a hidden day, returning a copy.
    // If the initial value of `date` is not a hidden day, don't do anything.
    // Pass `isExclusive` as `true` if you are dealing with an end date.
    // `inc` defaults to `1` (increment one day forward each time)
    skipHiddenDays: function(date, inc, isExclusive) {
        var out = date.clone();
        inc = inc || 1;
        while (
            this.isHiddenDayHash[(out.day() + (isExclusive ? inc : 0) + 7) % 7]
        ) {
            out.add(inc, 'days');
        }
        return out;
    },


    // Returns the date range of the full days the given range visually appears to occupy.
    // Returns a new range object.
    computeDayRange: function(range) {
        var startDay = range.start.clone().stripTime(); // the beginning of the day the range starts
        var end = range.end;
        var endDay = null;
        var endTimeMS;

        if (end) {
            endDay = end.clone().stripTime(); // the beginning of the day the range exclusively ends
            endTimeMS = +end.time(); // # of milliseconds into `endDay`

            // If the end time is actually inclusively part of the next day and is equal to or
            // beyond the next day threshold, adjust the end to be the exclusive end of `endDay`.
            // Otherwise, leaving it as inclusive will cause it to exclude `endDay`.
            if (endTimeMS && endTimeMS >= this.nextDayThreshold) {
                endDay.add(1, 'days');
            }
        }

        // If no end was specified, or if it is within `startDay` but not past nextDayThreshold,
        // assign the default duration of one day.
        if (!end || endDay <= startDay) {
            endDay = startDay.clone().add(1, 'days');
        }

        return { start: startDay, end: endDay };
    },


    // Does the given event visually appear to occupy more than one day?
    isMultiDayEvent: function(event) {
        var range = this.computeDayRange(event); // event is range-ish

        return range.end.diff(range.start, 'days') > 1;
    }

});



var Calendar = fc.Calendar = Class.extend({

    dirDefaults: null, // option defaults related to LTR or RTL
    langDefaults: null, // option defaults related to current locale
    overrides: null, // option overrides given to the fullCalendar constructor
    options: null, // all defaults combined with overrides
    viewSpecCache: null, // cache of view definitions
    view: null, // current View object
    header: null,
    loadingLevel: 0, // number of simultaneous loading tasks


    // a lot of this class' OOP logic is scoped within this constructor function,
    // but in the future, write individual methods on the prototype.
    constructor: Calendar_constructor,


    // Subclasses can override this for initialization logic after the constructor has been called
    initialize: function() {
    },


    // Initializes `this.options` and other important options-related objects
    initOptions: function(overrides) {
        var lang, langDefaults;
        var isRTL, dirDefaults;

        // converts legacy options into non-legacy ones.
        // in the future, when this is removed, don't use `overrides` reference. make a copy.
        overrides = massageOverrides(overrides);

        lang = overrides.lang;
        langDefaults = langOptionHash[lang];
        if (!langDefaults) {
            lang = Calendar.defaults.lang;
            langDefaults = langOptionHash[lang] || {};
        }

        isRTL = firstDefined(
            overrides.isRTL,
            langDefaults.isRTL,
            Calendar.defaults.isRTL
        );
        dirDefaults = isRTL ? Calendar.rtlDefaults : {};

        this.dirDefaults = dirDefaults;
        this.langDefaults = langDefaults;
        this.overrides = overrides;
        this.options = mergeOptions([ // merge defaults and overrides. lowest to highest precedence
            Calendar.defaults, // global defaults
            dirDefaults,
            langDefaults,
            overrides
        ]);
        populateInstanceComputableOptions(this.options);

        this.viewSpecCache = {}; // somewhat unrelated
    },


    // Gets information about how to create a view. Will use a cache.
    getViewSpec: function(viewType) {
        var cache = this.viewSpecCache;

        return cache[viewType] || (cache[viewType] = this.buildViewSpec(viewType));
    },


    // Given a duration singular unit, like "week" or "day", finds a matching view spec.
    // Preference is given to views that have corresponding buttons.
    getUnitViewSpec: function(unit) {
        var viewTypes;
        var i;
        var spec;

        if ($.inArray(unit, intervalUnits) != -1) {

            // put views that have buttons first. there will be duplicates, but oh well
            viewTypes = this.header.getViewsWithButtons();
            $.each(fc.views, function(viewType) { // all views
                viewTypes.push(viewType);
            });

            for (i = 0; i < viewTypes.length; i++) {
                spec = this.getViewSpec(viewTypes[i]);
                if (spec) {
                    if (spec.singleUnit == unit) {
                        return spec;
                    }
                }
            }
        }
    },


    // Builds an object with information on how to create a given view
    buildViewSpec: function(requestedViewType) {
        var viewOverrides = this.overrides.views || {};
        var specChain = []; // for the view. lowest to highest priority
        var defaultsChain = []; // for the view. lowest to highest priority
        var overridesChain = []; // for the view. lowest to highest priority
        var viewType = requestedViewType;
        var spec; // for the view
        var overrides; // for the view
        var duration;
        var unit;

        // iterate from the specific view definition to a more general one until we hit an actual View class
        while (viewType) {
            spec = fcViews[viewType];
            overrides = viewOverrides[viewType];
            viewType = null; // clear. might repopulate for another iteration

            if (typeof spec === 'function') { // TODO: deprecate
                spec = { 'class': spec };
            }

            if (spec) {
                specChain.unshift(spec);
                defaultsChain.unshift(spec.defaults || {});
                duration = duration || spec.duration;
                viewType = viewType || spec.type;
            }

            if (overrides) {
                overridesChain.unshift(overrides); // view-specific option hashes have options at zero-level
                duration = duration || overrides.duration;
                viewType = viewType || overrides.type;
            }
        }

        spec = mergeProps(specChain);
        spec.type = requestedViewType;
        if (!spec['class']) {
            return false;
        }

        if (duration) {
            duration = moment.duration(duration);
            if (duration.valueOf()) { // valid?
                spec.duration = duration;
                unit = computeIntervalUnit(duration);

                // view is a single-unit duration, like "week" or "day"
                // incorporate options for this. lowest priority
                if (duration.as(unit) === 1) {
                    spec.singleUnit = unit;
                    overridesChain.unshift(viewOverrides[unit] || {});
                }
            }
        }

        spec.defaults = mergeOptions(defaultsChain);
        spec.overrides = mergeOptions(overridesChain);

        this.buildViewSpecOptions(spec);
        this.buildViewSpecButtonText(spec, requestedViewType);

        return spec;
    },


    // Builds and assigns a view spec's options object from its already-assigned defaults and overrides
    buildViewSpecOptions: function(spec) {
        spec.options = mergeOptions([ // lowest to highest priority
            Calendar.defaults, // global defaults
            spec.defaults, // view's defaults (from ViewSubclass.defaults)
            this.dirDefaults,
            this.langDefaults, // locale and dir take precedence over view's defaults!
            this.overrides, // calendar's overrides (options given to constructor)
            spec.overrides // view's overrides (view-specific options)
        ]);
        populateInstanceComputableOptions(spec.options);
    },


    // Computes and assigns a view spec's buttonText-related options
    buildViewSpecButtonText: function(spec, requestedViewType) {

        // given an options object with a possible `buttonText` hash, lookup the buttonText for the
        // requested view, falling back to a generic unit entry like "week" or "day"
        function queryButtonText(options) {
            var buttonText = options.buttonText || {};
            return buttonText[requestedViewType] ||
                (spec.singleUnit ? buttonText[spec.singleUnit] : null);
        }

        // highest to lowest priority
        spec.buttonTextOverride =
            queryButtonText(this.overrides) || // constructor-specified buttonText lookup hash takes precedence
            spec.overrides.buttonText; // `buttonText` for view-specific options is a string

        // highest to lowest priority. mirrors buildViewSpecOptions
        spec.buttonTextDefault =
            queryButtonText(this.langDefaults) ||
            queryButtonText(this.dirDefaults) ||
            spec.defaults.buttonText || // a single string. from ViewSubclass.defaults
            queryButtonText(Calendar.defaults) ||
            (spec.duration ? this.humanizeDuration(spec.duration) : null) || // like "3 days"
            requestedViewType; // fall back to given view name
    },


    // Given a view name for a custom view or a standard view, creates a ready-to-go View object
    instantiateView: function(viewType) {
        var spec = this.getViewSpec(viewType);

        return new spec['class'](this, viewType, spec.options, spec.duration);
    },


    // Returns a boolean about whether the view is okay to instantiate at some point
    isValidViewType: function(viewType) {
        return Boolean(this.getViewSpec(viewType));
    },


    // Should be called when any type of async data fetching begins
    pushLoading: function() {
        if (!(this.loadingLevel++)) {
            this.trigger('loading', null, true, this.view);
        }
    },


    // Should be called when any type of async data fetching completes
    popLoading: function() {
        if (!(--this.loadingLevel)) {
            this.trigger('loading', null, false, this.view);
        }
    },


    // Given arguments to the select method in the API, returns a range
    buildSelectRange: function(start, end) {

        start = this.moment(start);
        if (end) {
            end = this.moment(end);
        }
        else if (start.hasTime()) {
            end = start.clone().add(this.defaultTimedEventDuration);
        }
        else {
            end = start.clone().add(this.defaultAllDayEventDuration);
        }

        return { start: start, end: end };
    }

});


Calendar.mixin(Emitter);


function Calendar_constructor(element, overrides) {
    var t = this;


    t.initOptions(overrides || {});
    var options = this.options;

    
    // Exports
    // -----------------------------------------------------------------------------------

    t.render = render;
    t.destroy = destroy;
    t.refetchEvents = refetchEvents;
    t.reportEvents = reportEvents;
    t.reportEventChange = reportEventChange;
    t.rerenderEvents = renderEvents; // `renderEvents` serves as a rerender. an API method
    t.changeView = renderView; // `renderView` will switch to another view
    t.select = select;
    t.unselect = unselect;
    t.prev = prev;
    t.next = next;
    t.prevYear = prevYear;
    t.nextYear = nextYear;
    t.today = today;
    t.gotoDate = gotoDate;
    t.incrementDate = incrementDate;
    t.zoomTo = zoomTo;
    t.getDate = getDate;
    t.getCalendar = getCalendar;
    t.getView = getView;
    t.option = option;
    t.trigger = trigger;



    // Language-data Internals
    // -----------------------------------------------------------------------------------
    // Apply overrides to the current language's data


    var localeData = createObject( // make a cheap copy
        getMomentLocaleData(options.lang) // will fall back to en
    );

    if (options.monthNames) {
        localeData._months = options.monthNames;
    }
    if (options.monthNamesShort) {
        localeData._monthsShort = options.monthNamesShort;
    }
    if (options.dayNames) {
        localeData._weekdays = options.dayNames;
    }
    if (options.dayNamesShort) {
        localeData._weekdaysShort = options.dayNamesShort;
    }
    if (options.firstDay != null) {
        var _week = createObject(localeData._week); // _week: { dow: # }
        _week.dow = options.firstDay;
        localeData._week = _week;
    }

    // assign a normalized value, to be used by our .week() moment extension
    localeData._fullCalendar_weekCalc = (function(weekCalc) {
        if (typeof weekCalc === 'function') {
            return weekCalc;
        }
        else if (weekCalc === 'local') {
            return weekCalc;
        }
        else if (weekCalc === 'iso' || weekCalc === 'ISO') {
            return 'ISO';
        }
    })(options.weekNumberCalculation);



    // Calendar-specific Date Utilities
    // -----------------------------------------------------------------------------------


    t.defaultAllDayEventDuration = moment.duration(options.defaultAllDayEventDuration);
    t.defaultTimedEventDuration = moment.duration(options.defaultTimedEventDuration);


    // Builds a moment using the settings of the current calendar: timezone and language.
    // Accepts anything the vanilla moment() constructor accepts.
    t.moment = function() {
        var mom;

        if (options.timezone === 'local') {
            mom = fc.moment.apply(null, arguments);

            // Force the moment to be local, because fc.moment doesn't guarantee it.
            if (mom.hasTime()) { // don't give ambiguously-timed moments a local zone
                mom.local();
            }
        }
        else if (options.timezone === 'UTC') {
            mom = fc.moment.utc.apply(null, arguments); // process as UTC
        }
        else {
            mom = fc.moment.parseZone.apply(null, arguments); // let the input decide the zone
        }

        if ('_locale' in mom) { // moment 2.8 and above
            mom._locale = localeData;
        }
        else { // pre-moment-2.8
            mom._lang = localeData;
        }

        return mom;
    };


    // Returns a boolean about whether or not the calendar knows how to calculate
    // the timezone offset of arbitrary dates in the current timezone.
    t.getIsAmbigTimezone = function() {
        return options.timezone !== 'local' && options.timezone !== 'UTC';
    };


    // Returns a copy of the given date in the current timezone of it is ambiguously zoned.
    // This will also give the date an unambiguous time.
    t.rezoneDate = function(date) {
        return t.moment(date.toArray());
    };


    // Returns a moment for the current date, as defined by the client's computer,
    // or overridden by the `now` option.
    t.getNow = function() {
        var now = options.now;
        if (typeof now === 'function') {
            now = now();
        }
        return t.moment(now);
    };


    // Get an event's normalized end date. If not present, calculate it from the defaults.
    t.getEventEnd = function(event) {
        if (event.end) {
            return event.end.clone();
        }
        else {
            return t.getDefaultEventEnd(event.allDay, event.start);
        }
    };


    // Given an event's allDay status and start date, return swhat its fallback end date should be.
    t.getDefaultEventEnd = function(allDay, start) { // TODO: rename to computeDefaultEventEnd
        var end = start.clone();

        if (allDay) {
            end.stripTime().add(t.defaultAllDayEventDuration);
        }
        else {
            end.add(t.defaultTimedEventDuration);
        }

        if (t.getIsAmbigTimezone()) {
            end.stripZone(); // we don't know what the tzo should be
        }

        return end;
    };


    // Produces a human-readable string for the given duration.
    // Side-effect: changes the locale of the given duration.
    t.humanizeDuration = function(duration) {
        return (duration.locale || duration.lang).call(duration, options.lang) // works moment-pre-2.8
            .humanize();
    };


    
    // Imports
    // -----------------------------------------------------------------------------------


    EventManager.call(t, options);
    var isFetchNeeded = t.isFetchNeeded;
    var fetchEvents = t.fetchEvents;



    // Locals
    // -----------------------------------------------------------------------------------


    var _element = element[0];
    var header;
    var headerElement;
    var content;
    var tm; // for making theme classes
    var currentView; // NOTE: keep this in sync with this.view
    var viewsByType = {}; // holds all instantiated view instances, current or not
    var suggestedViewHeight;
    var windowResizeProxy; // wraps the windowResize function
    var ignoreWindowResize = 0;
    var date;
    var events = [];
    
    
    
    // Main Rendering
    // -----------------------------------------------------------------------------------


    if (options.defaultDate != null) {
        date = t.moment(options.defaultDate);
    }
    else {
        date = t.getNow();
    }
    
    
    function render() {
        if (!content) {
            initialRender();
        }
        else if (elementVisible()) {
            // mainly for the public API
            calcSize();
            renderView();
        }
    }
    
    
    function initialRender() {
        tm = options.theme ? 'ui' : 'fc';
        element.addClass('fc');

        if (options.isRTL) {
            element.addClass('fc-rtl');
        }
        else {
            element.addClass('fc-ltr');
        }

        if (options.theme) {
            element.addClass('ui-widget');
        }
        else {
            element.addClass('fc-unthemed');
        }

        content = $("<div class='fc-view-container'/>").prependTo(element);

        header = t.header = new Header(t, options);
        headerElement = header.render();
        if (headerElement) {
            element.prepend(headerElement);
        }

        renderView(options.defaultView);

        if (options.handleWindowResize) {
            windowResizeProxy = debounce(windowResize, options.windowResizeDelay); // prevents rapid calls
            $(window).resize(windowResizeProxy);
        }
    }
    
    
    function destroy() {

        if (currentView) {
            currentView.removeElement();

            // NOTE: don't null-out currentView/t.view in case API methods are called after destroy.
            // It is still the "current" view, just not rendered.
        }

        header.removeElement();
        content.remove();
        element.removeClass('fc fc-ltr fc-rtl fc-unthemed ui-widget');

        if (windowResizeProxy) {
            $(window).unbind('resize', windowResizeProxy);
        }
    }
    
    
    function elementVisible() {
        return element.is(':visible');
    }
    
    

    // View Rendering
    // -----------------------------------------------------------------------------------


    // Renders a view because of a date change, view-type change, or for the first time.
    // If not given a viewType, keep the current view but render different dates.
    function renderView(viewType) {
        ignoreWindowResize++;

        // if viewType is changing, remove the old view's rendering
        if (currentView && viewType && currentView.type !== viewType) {
            header.deactivateButton(currentView.type);
            freezeContentHeight(); // prevent a scroll jump when view element is removed
            currentView.removeElement();
            currentView = t.view = null;
        }

        // if viewType changed, or the view was never created, create a fresh view
        if (!currentView && viewType) {
            currentView = t.view =
                viewsByType[viewType] ||
                (viewsByType[viewType] = t.instantiateView(viewType));

            currentView.setElement(
                $("<div class='fc-view fc-" + viewType + "-view' />").appendTo(content)
            );
            header.activateButton(viewType);
        }

        if (currentView) {

            // in case the view should render a period of time that is completely hidden
            date = currentView.massageCurrentDate(date);

            // render or rerender the view
            if (
                !currentView.displaying ||
                !date.isWithin(currentView.intervalStart, currentView.intervalEnd) // implicit date window change
            ) {
                if (elementVisible()) {

                    freezeContentHeight();
                    currentView.display(date);
                    unfreezeContentHeight(); // immediately unfreeze regardless of whether display is async

                    // need to do this after View::render, so dates are calculated
                    updateHeaderTitle();
                    updateTodayButton();

                    getAndRenderEvents();
                }
            }
        }

        unfreezeContentHeight(); // undo any lone freezeContentHeight calls
        ignoreWindowResize--;
    }

    

    // Resizing
    // -----------------------------------------------------------------------------------


    t.getSuggestedViewHeight = function() {
        if (suggestedViewHeight === undefined) {
            calcSize();
        }
        return suggestedViewHeight;
    };


    t.isHeightAuto = function() {
        return options.contentHeight === 'auto' || options.height === 'auto';
    };
    
    
    function updateSize(shouldRecalc) {
        if (elementVisible()) {

            if (shouldRecalc) {
                _calcSize();
            }

            ignoreWindowResize++;
            currentView.updateSize(true); // isResize=true. will poll getSuggestedViewHeight() and isHeightAuto()
            ignoreWindowResize--;

            return true; // signal success
        }
    }


    function calcSize() {
        if (elementVisible()) {
            _calcSize();
        }
    }
    
    
    function _calcSize() { // assumes elementVisible
        if (typeof options.contentHeight === 'number') { // exists and not 'auto'
            suggestedViewHeight = options.contentHeight;
        }
        else if (typeof options.height === 'number') { // exists and not 'auto'
            suggestedViewHeight = options.height - (headerElement ? headerElement.outerHeight(true) : 0);
        }
        else {
            suggestedViewHeight = Math.round(content.width() / Math.max(options.aspectRatio, .5));
        }
    }
    
    
    function windowResize(ev) {
        if (
            !ignoreWindowResize &&
            ev.target === window && // so we don't process jqui "resize" events that have bubbled up
            currentView.start // view has already been rendered
        ) {
            if (updateSize(true)) {
                currentView.trigger('windowResize', _element);
            }
        }
    }
    
    
    
    /* Event Fetching/Rendering
    -----------------------------------------------------------------------------*/
    // TODO: going forward, most of this stuff should be directly handled by the view


    function refetchEvents() { // can be called as an API method
        destroyEvents(); // so that events are cleared before user starts waiting for AJAX
        fetchAndRenderEvents();
    }


    function renderEvents() { // destroys old events if previously rendered
        if (elementVisible()) {
            freezeContentHeight();
            currentView.displayEvents(events);
            unfreezeContentHeight();
        }
    }


    function destroyEvents() {
        freezeContentHeight();
        currentView.clearEvents();
        unfreezeContentHeight();
    }
    

    function getAndRenderEvents() {
        if (!options.lazyFetching || isFetchNeeded(currentView.start, currentView.end)) {
            fetchAndRenderEvents();
        }
        else {
            renderEvents();
        }
    }


    function fetchAndRenderEvents() {
        fetchEvents(currentView.start, currentView.end);
            // ... will call reportEvents
            // ... which will call renderEvents
    }

    
    // called when event data arrives
    function reportEvents(_events) {
        events = _events;
        renderEvents();
    }


    // called when a single event's data has been changed
    function reportEventChange() {
        renderEvents();
    }



    /* Header Updating
    -----------------------------------------------------------------------------*/


    function updateHeaderTitle() {
        header.updateTitle(currentView.title);
    }


    function updateTodayButton() {
        var now = t.getNow();
        if (now.isWithin(currentView.intervalStart, currentView.intervalEnd)) {
            header.disableButton('today');
        }
        else {
            header.enableButton('today');
        }
    }
    


    /* Selection
    -----------------------------------------------------------------------------*/
    

    function select(start, end) {
        currentView.select(
            t.buildSelectRange.apply(t, arguments)
        );
    }
    

    function unselect() { // safe to be called before renderView
        if (currentView) {
            currentView.unselect();
        }
    }
    
    
    
    /* Date
    -----------------------------------------------------------------------------*/
    
    
    function prev() {
        date = currentView.computePrevDate(date);
        renderView();
    }
    
    
    function next() {
        date = currentView.computeNextDate(date);
        renderView();
    }
    
    
    function prevYear() {
        date.add(-1, 'years');
        renderView();
    }
    
    
    function nextYear() {
        date.add(1, 'years');
        renderView();
    }
    
    
    function today() {
        date = t.getNow();
        renderView();
    }
    
    
    function gotoDate(dateInput) {
        date = t.moment(dateInput);
        renderView();
    }
    
    
    function incrementDate(delta) {
        date.add(moment.duration(delta));
        renderView();
    }


    // Forces navigation to a view for the given date.
    // `viewType` can be a specific view name or a generic one like "week" or "day".
    function zoomTo(newDate, viewType) {
        var spec;

        viewType = viewType || 'day'; // day is default zoom
        spec = t.getViewSpec(viewType) || t.getUnitViewSpec(viewType);

        date = newDate;
        renderView(spec ? spec.type : null);
    }
    
    
    function getDate() {
        return date.clone();
    }



    /* Height "Freezing"
    -----------------------------------------------------------------------------*/
    // TODO: move this into the view


    function freezeContentHeight() {
        content.css({
            width: '100%',
            height: content.height(),
            overflow: 'hidden'
        });
    }


    function unfreezeContentHeight() {
        content.css({
            width: '',
            height: '',
            overflow: ''
        });
    }
    
    
    
    /* Misc
    -----------------------------------------------------------------------------*/
    

    function getCalendar() {
        return t;
    }

    
    function getView() {
        return currentView;
    }
    
    
    function option(name, value) {
        if (value === undefined) {
            return options[name];
        }
        if (name == 'height' || name == 'contentHeight' || name == 'aspectRatio') {
            options[name] = value;
            updateSize(true); // true = allow recalculation of height
        }
    }
    
    
    function trigger(name, thisObj) { // overrides the Emitter's trigger method :(
        var args = Array.prototype.slice.call(arguments, 2);

        thisObj = thisObj || _element;
        this.triggerWith(name, thisObj, args); // Emitter's method

        if (options[name]) {
            return options[name].apply(thisObj, args);
        }
    }

    t.initialize();
}



Calendar.defaults = {

    titleRangeSeparator: ' \u2014 ', // emphasized dash
    monthYearFormat: 'MMMM YYYY', // required for en. other languages rely on datepicker computable option

    defaultTimedEventDuration: '02:00:00',
    defaultAllDayEventDuration: { days: 1 },
    forceEventDuration: false,
    nextDayThreshold: '09:00:00', // 9am

    // display
    defaultView: 'month',
    aspectRatio: 1.35,
    header: {
        left: 'title',
        center: '',
        right: 'today prev,next'
    },
    weekends: true,
    weekNumbers: false,

    weekNumberTitle: 'W',
    weekNumberCalculation: 'local',
    
    //editable: false,

    scrollTime: '06:00:00',
    
    // event ajax
    lazyFetching: true,
    startParam: 'start',
    endParam: 'end',
    timezoneParam: 'timezone',

    timezone: false,

    //allDayDefault: undefined,

    // locale
    isRTL: false,
    buttonText: {
        prev: "prev",
        next: "next",
        prevYear: "prev year",
        nextYear: "next year",
        year: 'year', // TODO: locale files need to specify this
        today: 'today',
        month: 'month',
        week: 'week',
        day: 'day'
    },

    buttonIcons: {
        prev: 'left-single-arrow',
        next: 'right-single-arrow',
        prevYear: 'left-double-arrow',
        nextYear: 'right-double-arrow'
    },
    
    // jquery-ui theming
    theme: false,
    themeButtonIcons: {
        prev: 'circle-triangle-w',
        next: 'circle-triangle-e',
        prevYear: 'seek-prev',
        nextYear: 'seek-next'
    },

    //eventResizableFromStart: false,
    dragOpacity: .75,
    dragRevertDuration: 500,
    dragScroll: true,
    
    //selectable: false,
    unselectAuto: true,
    
    dropAccept: '*',

    eventOrder: 'title',

    eventLimit: false,
    eventLimitText: 'more',
    eventLimitClick: 'popover',
    dayPopoverFormat: 'LL',
    
    handleWindowResize: true,
    windowResizeDelay: 200, // milliseconds before an updateSize happens
    editor: null
    
};


Calendar.englishDefaults = { // used by lang.js
    dayPopoverFormat: 'dddd, MMMM D'
};


Calendar.rtlDefaults = { // right-to-left defaults
    header: { // TODO: smarter solution (first/center/last ?)
        left: 'next,prev today',
        center: '',
        right: 'title'
    },
    buttonIcons: {
        prev: 'right-single-arrow',
        next: 'left-single-arrow',
        prevYear: 'right-double-arrow',
        nextYear: 'left-double-arrow'
    },
    themeButtonIcons: {
        prev: 'circle-triangle-e',
        next: 'circle-triangle-w',
        nextYear: 'seek-prev',
        prevYear: 'seek-next'
    }
};



var langOptionHash = fc.langs = {}; // initialize and expose


// TODO: document the structure and ordering of a FullCalendar lang file
// TODO: rename everything "lang" to "locale", like what the moment project did


// Initialize jQuery UI datepicker translations while using some of the translations
// Will set this as the default language for datepicker.
fc.datepickerLang = function(langCode, dpLangCode, dpOptions) {

    // get the FullCalendar internal option hash for this language. create if necessary
    var fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

    // transfer some simple options from datepicker to fc
    fcOptions.isRTL = dpOptions.isRTL;
    fcOptions.weekNumberTitle = dpOptions.weekHeader;

    // compute some more complex options from datepicker
    $.each(dpComputableOptions, function(name, func) {
        fcOptions[name] = func(dpOptions);
    });

    // is jQuery UI Datepicker is on the page?
    if ($.datepicker) {

        // Register the language data.
        // FullCalendar and MomentJS use language codes like "pt-br" but Datepicker
        // does it like "pt-BR" or if it doesn't have the language, maybe just "pt".
        // Make an alias so the language can be referenced either way.
        $.datepicker.regional[dpLangCode] =
            $.datepicker.regional[langCode] = // alias
                dpOptions;

        // Alias 'en' to the default language data. Do this every time.
        $.datepicker.regional.en = $.datepicker.regional[''];

        // Set as Datepicker's global defaults.
        $.datepicker.setDefaults(dpOptions);
    }
};


// Sets FullCalendar-specific translations. Will set the language as the global default.
fc.lang = function(langCode, newFcOptions) {
    var fcOptions;
    var momOptions;

    // get the FullCalendar internal option hash for this language. create if necessary
    fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

    // provided new options for this language? merge them in
    if (newFcOptions) {
        fcOptions = langOptionHash[langCode] = mergeOptions([ fcOptions, newFcOptions ]);
    }

    // compute language options that weren't defined.
    // always do this. newFcOptions can be undefined when initializing from i18n file,
    // so no way to tell if this is an initialization or a default-setting.
    momOptions = getMomentLocaleData(langCode); // will fall back to en
    $.each(momComputableOptions, function(name, func) {
        if (fcOptions[name] == null) {
            fcOptions[name] = func(momOptions, fcOptions);
        }
    });

    // set it as the default language for FullCalendar
    Calendar.defaults.lang = langCode;
};


// NOTE: can't guarantee any of these computations will run because not every language has datepicker
// configs, so make sure there are English fallbacks for these in the defaults file.
var dpComputableOptions = {

    buttonText: function(dpOptions) {
        return {
            // the translations sometimes wrongly contain HTML entities
            prev: stripHtmlEntities(dpOptions.prevText),
            next: stripHtmlEntities(dpOptions.nextText),
            today: stripHtmlEntities(dpOptions.currentText)
        };
    },

    // Produces format strings like "MMMM YYYY" -> "September 2014"
    monthYearFormat: function(dpOptions) {
        return dpOptions.showMonthAfterYear ?
            'YYYY[' + dpOptions.yearSuffix + '] MMMM' :
            'MMMM YYYY[' + dpOptions.yearSuffix + ']';
    }

};

var momComputableOptions = {

    // Produces format strings like "ddd M/D" -> "Fri 9/15"
    dayOfMonthFormat: function(momOptions, fcOptions) {
        var format = momOptions.longDateFormat('l'); // for the format like "M/D/YYYY"

        // strip the year off the edge, as well as other misc non-whitespace chars
        format = format.replace(/^Y+[^\w\s]*|[^\w\s]*Y+$/g, '');

        if (fcOptions.isRTL) {
            format += ' ddd'; // for RTL, add day-of-week to end
        }
        else {
            format = 'ddd ' + format; // for LTR, add day-of-week to beginning
        }
        return format;
    },

    // Produces format strings like "h:mma" -> "6:00pm"
    mediumTimeFormat: function(momOptions) { // can't be called `timeFormat` because collides with option
        return momOptions.longDateFormat('LT')
            .replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
    },

    // Produces format strings like "h(:mm)a" -> "6pm" / "6:30pm"
    smallTimeFormat: function(momOptions) {
        return momOptions.longDateFormat('LT')
            .replace(':mm', '(:mm)')
            .replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
            .replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
    },

    // Produces format strings like "h(:mm)t" -> "6p" / "6:30p"
    extraSmallTimeFormat: function(momOptions) {
        return momOptions.longDateFormat('LT')
            .replace(':mm', '(:mm)')
            .replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
            .replace(/\s*a$/i, 't'); // convert to AM/PM/am/pm to lowercase one-letter. remove any spaces beforehand
    },

    // Produces format strings like "ha" / "H" -> "6pm" / "18"
    hourFormat: function(momOptions) {
        return momOptions.longDateFormat('LT')
            .replace(':mm', '')
            .replace(/(\Wmm)$/, '') // like above, but for foreign langs
            .replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
    },

    // Produces format strings like "h:mm" -> "6:30" (with no AM/PM)
    noMeridiemTimeFormat: function(momOptions) {
        return momOptions.longDateFormat('LT')
            .replace(/\s*a$/i, ''); // remove trailing AM/PM
    }

};


// options that should be computed off live calendar options (considers override options)
var instanceComputableOptions = { // TODO: best place for this? related to lang?

    // Produces format strings for results like "Mo 16"
    smallDayDateFormat: function(options) {
        return options.isRTL ?
            'D dd' :
            'dd D';
    },

    // Produces format strings for results like "Wk 5"
    weekFormat: function(options) {
        return options.isRTL ?
            'w[ ' + options.weekNumberTitle + ']' :
            '[' + options.weekNumberTitle + ' ]w';
    },

    // Produces format strings for results like "Wk5"
    smallWeekFormat: function(options) {
        return options.isRTL ?
            'w[' + options.weekNumberTitle + ']' :
            '[' + options.weekNumberTitle + ']w';
    }

};

function populateInstanceComputableOptions(options) {
    $.each(instanceComputableOptions, function(name, func) {
        if (options[name] == null) {
            options[name] = func(options);
        }
    });
}


// Returns moment's internal locale data. If doesn't exist, returns English.
// Works with moment-pre-2.8
function getMomentLocaleData(langCode) {
    var func = moment.localeData || moment.langData;
    return func.call(moment, langCode) ||
        func.call(moment, 'en'); // the newer localData could return null, so fall back to en
}


// Initialize English by forcing computation of moment-derived options.
// Also, sets it as the default.
fc.lang('en', Calendar.englishDefaults);



/* Top toolbar area with buttons and title
----------------------------------------------------------------------------------------------------------------------*/
// TODO: rename all header-related things to "toolbar"

function Header(calendar, options) {
    var t = this;
    
    // exports
    t.render = render;
    t.removeElement = removeElement;
    t.updateTitle = updateTitle;
    t.activateButton = activateButton;
    t.deactivateButton = deactivateButton;
    t.disableButton = disableButton;
    t.enableButton = enableButton;
    t.getViewsWithButtons = getViewsWithButtons;
    
    // locals
    var el = $();
    var viewsWithButtons = [];
    var tm;


    function render() {
        var sections = options.header;

        tm = options.theme ? 'ui' : 'fc';

        if (sections) {
            el = $("<div class='fc-toolbar'/>")
                .append(renderSection('left'))
                .append(renderSection('right'))
                .append(renderSection('center'))
                .append('<div class="fc-clear"/>');

            return el;
        }
    }
    
    
    function removeElement() {
        el.remove();
        el = $();
    }
    
    
    function renderSection(position) {
        var sectionEl = $('<div class="fc-' + position + '"/>');
        var buttonStr = options.header[position];

        if (buttonStr) {
            $.each(buttonStr.split(' '), function(i) {
                var groupChildren = $();
                var isOnlyButtons = true;
                var groupEl;

                $.each(this.split(','), function(j, buttonName) {
                    var customButtonProps;
                    var viewSpec;
                    var buttonClick;
                    var overrideText; // text explicitly set by calendar's constructor options. overcomes icons
                    var defaultText;
                    var themeIcon;
                    var normalIcon;
                    var innerHtml;
                    var classes;
                    var button; // the element

                    if (buttonName == 'title') {
                        groupChildren = groupChildren.add($('<h2>&nbsp;</h2>')); // we always want it to take up height
                        isOnlyButtons = false;
                    }
                    else {
                        if ((customButtonProps = (calendar.options.customButtons || {})[buttonName])) {
                            buttonClick = function(ev) {
                                if (customButtonProps.click) {
                                    customButtonProps.click.call(button[0], ev);
                                }
                            };
                            overrideText = ''; // icons will override text
                            defaultText = customButtonProps.text;
                        }
                        else if ((viewSpec = calendar.getViewSpec(buttonName))) {
                            buttonClick = function() {
                                calendar.changeView(buttonName);
                            };
                            viewsWithButtons.push(buttonName);
                            overrideText = viewSpec.buttonTextOverride;
                            defaultText = viewSpec.buttonTextDefault;
                        }
                        else if (calendar[buttonName]) { // a calendar method
                            buttonClick = function() {
                                calendar[buttonName]();
                            };
                            overrideText = (calendar.overrides.buttonText || {})[buttonName];
                            defaultText = options.buttonText[buttonName]; // everything else is considered default
                        }

                        if (buttonClick) {

                            themeIcon =
                                customButtonProps ?
                                    customButtonProps.themeIcon :
                                    options.themeButtonIcons[buttonName];

                            normalIcon =
                                customButtonProps ?
                                    customButtonProps.icon :
                                    options.buttonIcons[buttonName];

                            if (overrideText) {
                                innerHtml = htmlEscape(overrideText);
                            }
                            else if (themeIcon && options.theme) {
                                innerHtml = "<span class='ui-icon ui-icon-" + themeIcon + "'></span>";
                            }
                            else if (normalIcon && !options.theme) {
                                innerHtml = "<span class='fc-icon fc-icon-" + normalIcon + "'></span>";
                            }
                            else {
                                innerHtml = htmlEscape(defaultText);
                            }

                            classes = [
                                'fc-' + buttonName + '-button',
                                tm + '-button',
                                tm + '-state-default'
                            ];

                            button = $( // type="button" so that it doesn't submit a form
                                '<button type="button" class="' + classes.join(' ') + '">' +
                                    innerHtml +
                                '</button>'
                                )
                                .click(function(ev) {
                                    // don't process clicks for disabled buttons
                                    if (!button.hasClass(tm + '-state-disabled')) {

                                        buttonClick(ev);

                                        // after the click action, if the button becomes the "active" tab, or disabled,
                                        // it should never have a hover class, so remove it now.
                                        if (
                                            button.hasClass(tm + '-state-active') ||
                                            button.hasClass(tm + '-state-disabled')
                                        ) {
                                            button.removeClass(tm + '-state-hover');
                                        }
                                    }
                                })
                                .mousedown(function() {
                                    // the *down* effect (mouse pressed in).
                                    // only on buttons that are not the "active" tab, or disabled
                                    button
                                        .not('.' + tm + '-state-active')
                                        .not('.' + tm + '-state-disabled')
                                        .addClass(tm + '-state-down');
                                })
                                .mouseup(function() {
                                    // undo the *down* effect
                                    button.removeClass(tm + '-state-down');
                                })
                                .hover(
                                    function() {
                                        // the *hover* effect.
                                        // only on buttons that are not the "active" tab, or disabled
                                        button
                                            .not('.' + tm + '-state-active')
                                            .not('.' + tm + '-state-disabled')
                                            .addClass(tm + '-state-hover');
                                    },
                                    function() {
                                        // undo the *hover* effect
                                        button
                                            .removeClass(tm + '-state-hover')
                                            .removeClass(tm + '-state-down'); // if mouseleave happens before mouseup
                                    }
                                );

                            groupChildren = groupChildren.add(button);
                        }
                    }
                });

                if (isOnlyButtons) {
                    groupChildren
                        .first().addClass(tm + '-corner-left').end()
                        .last().addClass(tm + '-corner-right').end();
                }

                if (groupChildren.length > 1) {
                    groupEl = $('<div/>');
                    if (isOnlyButtons) {
                        groupEl.addClass('fc-button-group');
                    }
                    groupEl.append(groupChildren);
                    sectionEl.append(groupEl);
                }
                else {
                    sectionEl.append(groupChildren); // 1 or 0 children
                }
            });
        }

        return sectionEl;
    }
    
    
    function updateTitle(text) {
        el.find('h2').text(text);
    }
    
    
    function activateButton(buttonName) {
        el.find('.fc-' + buttonName + '-button')
            .addClass(tm + '-state-active');
    }
    
    
    function deactivateButton(buttonName) {
        el.find('.fc-' + buttonName + '-button')
            .removeClass(tm + '-state-active');
    }
    
    
    function disableButton(buttonName) {
        el.find('.fc-' + buttonName + '-button')
            .attr('disabled', 'disabled')
            .addClass(tm + '-state-disabled');
    }
    
    
    function enableButton(buttonName) {
        el.find('.fc-' + buttonName + '-button')
            .removeAttr('disabled')
            .removeClass(tm + '-state-disabled');
    }


    function getViewsWithButtons() {
        return viewsWithButtons;
    }

}



fc.sourceNormalizers = [];
fc.sourceFetchers = [];

var ajaxDefaults = {
    dataType: 'json',
    cache: false
};

var eventGUID = 1;


function EventManager(options) { // assumed to be a calendar
    var t = this;
    
    
    // exports
    t.isFetchNeeded = isFetchNeeded;
    t.fetchEvents = fetchEvents;
    t.addEventSource = addEventSource;
    t.removeEventSource = removeEventSource;
    t.updateEvent = updateEvent;
    t.renderEvent = renderEvent;
    t.removeEvents = removeEvents;
    t.clientEvents = clientEvents;
    t.mutateEvent = mutateEvent;
    t.normalizeEventRange = normalizeEventRange;
    t.normalizeEventRangeTimes = normalizeEventRangeTimes;
    t.ensureVisibleEventRange = ensureVisibleEventRange;
    
    
    // imports
    var reportEvents = t.reportEvents;
    
    
    // locals
    var stickySource = { events: [] };
    var sources = [ stickySource ];
    var rangeStart, rangeEnd;
    var currentFetchID = 0;
    var pendingSourceCnt = 0;
    var cache = []; // holds events that have already been expanded


    $.each(
        (options.events ? [ options.events ] : []).concat(options.eventSources || []),
        function(i, sourceInput) {
            var source = buildEventSource(sourceInput);
            if (source) {
                sources.push(source);
            }
        }
    );
    
    
    
    /* Fetching
    -----------------------------------------------------------------------------*/
    
    
    function isFetchNeeded(start, end) {
        return !rangeStart || // nothing has been fetched yet?
            // or, a part of the new range is outside of the old range? (after normalizing)
            start.clone().stripZone() < rangeStart.clone().stripZone() ||
            end.clone().stripZone() > rangeEnd.clone().stripZone();
    }
    
    
    function fetchEvents(start, end) {
        rangeStart = start;
        rangeEnd = end;
        cache = [];
        var fetchID = ++currentFetchID;
        var len = sources.length;
        pendingSourceCnt = len;
        for (var i=0; i<len; i++) {
            fetchEventSource(sources[i], fetchID);
        }
    }
    
    
    function fetchEventSource(source, fetchID) {
        _fetchEventSource(source, function(eventInputs) {
            var isArraySource = $.isArray(source.events);
            var i, eventInput;
            var abstractEvent;

            if (fetchID == currentFetchID) {

                if (eventInputs) {
                    for (i = 0; i < eventInputs.length; i++) {
                        eventInput = eventInputs[i];

                        if (isArraySource) { // array sources have already been convert to Event Objects
                            abstractEvent = eventInput;
                        }
                        else {
                            abstractEvent = buildEventFromInput(eventInput, source);
                        }

                        if (abstractEvent) { // not false (an invalid event)
                            cache.push.apply(
                                cache,
                                expandEvent(abstractEvent) // add individual expanded events to the cache
                            );
                        }
                    }
                }

                pendingSourceCnt--;
                if (!pendingSourceCnt) {
                    reportEvents(cache);
                }
            }
        });
    }
    
    
    function _fetchEventSource(source, callback) {
        var i;
        var fetchers = fc.sourceFetchers;
        var res;

        for (i=0; i<fetchers.length; i++) {
            res = fetchers[i].call(
                t, // this, the Calendar object
                source,
                rangeStart.clone(),
                rangeEnd.clone(),
                options.timezone,
                callback
            );

            if (res === true) {
                // the fetcher is in charge. made its own async request
                return;
            }
            else if (typeof res == 'object') {
                // the fetcher returned a new source. process it
                _fetchEventSource(res, callback);
                return;
            }
        }

        var events = source.events;
        if (events) {
            if ($.isFunction(events)) {
                t.pushLoading();
                events.call(
                    t, // this, the Calendar object
                    rangeStart.clone(),
                    rangeEnd.clone(),
                    options.timezone,
                    function(events) {
                        callback(events);
                        t.popLoading();
                    }
                );
            }
            else if ($.isArray(events)) {
                callback(events);
            }
            else {
                callback();
            }
        }else{
            var url = source.url;
            if (url) {
                var success = source.success;
                var error = source.error;
                var complete = source.complete;

                // retrieve any outbound GET/POST $.ajax data from the options
                var customData;
                if ($.isFunction(source.data)) {
                    // supplied as a function that returns a key/value object
                    customData = source.data();
                }
                else {
                    // supplied as a straight key/value object
                    customData = source.data;
                }

                // use a copy of the custom data so we can modify the parameters
                // and not affect the passed-in object.
                var data = $.extend({}, customData || {});

                var startParam = firstDefined(source.startParam, options.startParam);
                var endParam = firstDefined(source.endParam, options.endParam);
                var timezoneParam = firstDefined(source.timezoneParam, options.timezoneParam);

                if (startParam) {
                    data[startParam] = rangeStart.format();
                }
                if (endParam) {
                    data[endParam] = rangeEnd.format();
                }
                if (options.timezone && options.timezone != 'local') {
                    data[timezoneParam] = options.timezone;
                }

                t.pushLoading();
                $.ajax($.extend({}, ajaxDefaults, source, {
                    data: data,
                    success: function(events) {
                        events = events || [];
                        var res = applyAll(success, this, arguments);
                        if ($.isArray(res)) {
                            events = res;
                        }
                        callback(events);
                    },
                    error: function() {
                        applyAll(error, this, arguments);
                        callback();
                    },
                    complete: function() {
                        applyAll(complete, this, arguments);
                        t.popLoading();
                    }
                }));
            }else{
                callback();
            }
        }
    }
    
    
    
    /* Sources
    -----------------------------------------------------------------------------*/
    

    function addEventSource(sourceInput) {
        var source = buildEventSource(sourceInput);
        if (source) {
            sources.push(source);
            pendingSourceCnt++;
            fetchEventSource(source, currentFetchID); // will eventually call reportEvents
        }
    }


    function buildEventSource(sourceInput) { // will return undefined if invalid source
        var normalizers = fc.sourceNormalizers;
        var source;
        var i;

        if ($.isFunction(sourceInput) || $.isArray(sourceInput)) {
            source = { events: sourceInput };
        }
        else if (typeof sourceInput === 'string') {
            source = { url: sourceInput };
        }
        else if (typeof sourceInput === 'object') {
            source = $.extend({}, sourceInput); // shallow copy
        }

        if (source) {

            // TODO: repeat code, same code for event classNames
            if (source.className) {
                if (typeof source.className === 'string') {
                    source.className = source.className.split(/\s+/);
                }
                // otherwise, assumed to be an array
            }
            else {
                source.className = [];
            }

            // for array sources, we convert to standard Event Objects up front
            if ($.isArray(source.events)) {
                source.origArray = source.events; // for removeEventSource
                source.events = $.map(source.events, function(eventInput) {
                    return buildEventFromInput(eventInput, source);
                });
            }

            for (i=0; i<normalizers.length; i++) {
                normalizers[i].call(t, source);
            }

            return source;
        }
    }


    function removeEventSource(source) {
        sources = $.grep(sources, function(src) {
            return !isSourcesEqual(src, source);
        });
        // remove all client events from that source
        cache = $.grep(cache, function(e) {
            return !isSourcesEqual(e.source, source);
        });
        reportEvents(cache);
    }


    function isSourcesEqual(source1, source2) {
        return source1 && source2 && getSourcePrimitive(source1) == getSourcePrimitive(source2);
    }


    function getSourcePrimitive(source) {
        return (
            (typeof source === 'object') ? // a normalized event source?
                (source.origArray || source.googleCalendarId || source.url || source.events) : // get the primitive
                null
        ) ||
        source; // the given argument *is* the primitive
    }
    
    
    
    /* Manipulation
    -----------------------------------------------------------------------------*/


    // Only ever called from the externally-facing API
    function updateEvent(event) {

        // massage start/end values, even if date string values
        event.start = t.moment(event.start);
        if (event.end) {
            event.end = t.moment(event.end);
        }
        else {
            event.end = null;
        }

        mutateEvent(event, getMiscEventProps(event)); // will handle start/end/allDay normalization
        reportEvents(cache); // reports event modifications (so we can redraw)
    }


    // Returns a hash of misc event properties that should be copied over to related events.
    function getMiscEventProps(event) {
        var props = {};

        $.each(event, function(name, val) {
            if (isMiscEventPropName(name)) {
                if (val !== undefined && isAtomic(val)) { // a defined non-object
                    props[name] = val;
                }
            }
        });

        return props;
    }

    // non-date-related, non-id-related, non-secret
    function isMiscEventPropName(name) {
        return !/^_|^(id|allDay|start|end)$/.test(name);
    }

    
    // returns the expanded events that were created
    function renderEvent(eventInput, stick) {
        var abstractEvent = buildEventFromInput(eventInput);
        var events;
        var i, event;

        if (abstractEvent) { // not false (a valid input)
            events = expandEvent(abstractEvent);

            for (i = 0; i < events.length; i++) {
                event = events[i];

                if (!event.source) {
                    if (stick) {
                        stickySource.events.push(event);
                        event.source = stickySource;
                    }
                    cache.push(event);
                }
            }

            reportEvents(cache);

            return events;
        }

        return [];
    }
    
    
    function removeEvents(filter) {
        var eventID;
        var i;

        if (filter == null) { // null or undefined. remove all events
            filter = function() { return true; }; // will always match
        }
        else if (!$.isFunction(filter)) { // an event ID
            eventID = filter + '';
            filter = function(event) {
                return event._id == eventID;
            };
        }

        // Purge event(s) from our local cache
        cache = $.grep(cache, filter, true); // inverse=true

        // Remove events from array sources.
        // This works because they have been converted to official Event Objects up front.
        // (and as a result, event._id has been calculated).
        for (i=0; i<sources.length; i++) {
            if ($.isArray(sources[i].events)) {
                sources[i].events = $.grep(sources[i].events, filter, true);
            }
        }

        reportEvents(cache);
    }
    
    
    function clientEvents(filter) {
        if ($.isFunction(filter)) {
            return $.grep(cache, filter);
        }
        else if (filter != null) { // not null, not undefined. an event ID
            filter += '';
            return $.grep(cache, function(e) {
                return e._id == filter;
            });
        }
        return cache; // else, return all
    }
    
    
    
    /* Event Normalization
    -----------------------------------------------------------------------------*/


    // Given a raw object with key/value properties, returns an "abstract" Event object.
    // An "abstract" event is an event that, if recurring, will not have been expanded yet.
    // Will return `false` when input is invalid.
    // `source` is optional
    function buildEventFromInput(input, source) {
        var out = {};
        var start, end;
        var allDay;

        if (options.eventDataTransform) {
            input = options.eventDataTransform(input);
        }
        if (source && source.eventDataTransform) {
            input = source.eventDataTransform(input);
        }

        // Copy all properties over to the resulting object.
        // The special-case properties will be copied over afterwards.
        $.extend(out, input);

        if (source) {
            out.source = source;
        }

        out._id = input._id || (input.id === undefined ? '_fc' + eventGUID++ : input.id + '');

        if (input.className) {
            if (typeof input.className == 'string') {
                out.className = input.className.split(/\s+/);
            }
            else { // assumed to be an array
                out.className = input.className;
            }
        }
        else {
            out.className = [];
        }

        start = input.start || input.date; // "date" is an alias for "start"
        end = input.end;

        // parse as a time (Duration) if applicable
        if (isTimeString(start)) {
            start = moment.duration(start);
        }
        if (isTimeString(end)) {
            end = moment.duration(end);
        }

        if (input.dow || moment.isDuration(start) || moment.isDuration(end)) {

            // the event is "abstract" (recurring) so don't calculate exact start/end dates just yet
            out.start = start ? moment.duration(start) : null; // will be a Duration or null
            out.end = end ? moment.duration(end) : null; // will be a Duration or null
            out._recurring = true; // our internal marker
        }
        else {

            if (start) {
                start = t.moment(start);
                if (!start.isValid()) {
                    return false;
                }
            }

            if (end) {
                end = t.moment(end);
                if (!end.isValid()) {
                    end = null; // let defaults take over
                }
            }

            allDay = input.allDay;
            if (allDay === undefined) { // still undefined? fallback to default
                allDay = firstDefined(
                    source ? source.allDayDefault : undefined,
                    options.allDayDefault
                );
                // still undefined? normalizeEventRange will calculate it
            }

            assignDatesToEvent(start, end, allDay, out);
        }

        return out;
    }


    // Normalizes and assigns the given dates to the given partially-formed event object.
    // NOTE: mutates the given start/end moments. does not make a copy.
    function assignDatesToEvent(start, end, allDay, event) {
        event.start = start;
        event.end = end;
        event.allDay = allDay;
        normalizeEventRange(event);
        backupEventDates(event);
    }


    // Ensures proper values for allDay/start/end. Accepts an Event object, or a plain object with event-ish properties.
    // NOTE: Will modify the given object.
    function normalizeEventRange(props) {

        normalizeEventRangeTimes(props);

        if (props.end && !props.end.isAfter(props.start)) {
            props.end = null;
        }

        if (!props.end) {
            if (options.forceEventDuration) {
                props.end = t.getDefaultEventEnd(props.allDay, props.start);
            }
            else {
                props.end = null;
            }
        }
    }


    // Ensures the allDay property exists and the timeliness of the start/end dates are consistent
    function normalizeEventRangeTimes(range) {
        if (range.allDay == null) {
            range.allDay = !(range.start.hasTime() || (range.end && range.end.hasTime()));
        }

        if (range.allDay) {
            range.start.stripTime();
            if (range.end) {
                // TODO: consider nextDayThreshold here? If so, will require a lot of testing and adjustment
                range.end.stripTime();
            }
        }
        else {
            if (!range.start.hasTime()) {
                range.start = t.rezoneDate(range.start); // will assign a 00:00 time
            }
            if (range.end && !range.end.hasTime()) {
                range.end = t.rezoneDate(range.end); // will assign a 00:00 time
            }
        }
    }


    // If `range` is a proper range with a start and end, returns the original object.
    // If missing an end, computes a new range with an end, computing it as if it were an event.
    // TODO: make this a part of the event -> eventRange system
    function ensureVisibleEventRange(range) {
        var allDay;

        if (!range.end) {

            allDay = range.allDay; // range might be more event-ish than we think
            if (allDay == null) {
                allDay = !range.start.hasTime();
            }

            range = $.extend({}, range); // make a copy, copying over other misc properties
            range.end = t.getDefaultEventEnd(allDay, range.start);
        }
        return range;
    }


    // If the given event is a recurring event, break it down into an array of individual instances.
    // If not a recurring event, return an array with the single original event.
    // If given a falsy input (probably because of a failed buildEventFromInput call), returns an empty array.
    // HACK: can override the recurring window by providing custom rangeStart/rangeEnd (for businessHours).
    function expandEvent(abstractEvent, _rangeStart, _rangeEnd) {
        var events = [];
        var dowHash;
        var dow;
        var i;
        var date;
        var startTime, endTime;
        var start, end;
        var event;

        _rangeStart = _rangeStart || rangeStart;
        _rangeEnd = _rangeEnd || rangeEnd;

        if (abstractEvent) {
            if (abstractEvent._recurring) {

                // make a boolean hash as to whether the event occurs on each day-of-week
                if ((dow = abstractEvent.dow)) {
                    dowHash = {};
                    for (i = 0; i < dow.length; i++) {
                        dowHash[dow[i]] = true;
                    }
                }

                // iterate through every day in the current range
                date = _rangeStart.clone().stripTime(); // holds the date of the current day
                while (date.isBefore(_rangeEnd)) {

                    if (!dowHash || dowHash[date.day()]) { // if everyday, or this particular day-of-week

                        startTime = abstractEvent.start; // the stored start and end properties are times (Durations)
                        endTime = abstractEvent.end; // "
                        start = date.clone();
                        end = null;

                        if (startTime) {
                            start = start.time(startTime);
                        }
                        if (endTime) {
                            end = date.clone().time(endTime);
                        }

                        event = $.extend({}, abstractEvent); // make a copy of the original
                        assignDatesToEvent(
                            start, end,
                            !startTime && !endTime, // allDay?
                            event
                        );
                        events.push(event);
                    }

                    date.add(1, 'days');
                }
            }
            else {
                events.push(abstractEvent); // return the original event. will be a one-item array
            }
        }

        return events;
    }



    /* Event Modification Math
    -----------------------------------------------------------------------------------------*/


    // Modifies an event and all related events by applying the given properties.
    // Special date-diffing logic is used for manipulation of dates.
    // If `props` does not contain start/end dates, the updated values are assumed to be the event's current start/end.
    // All date comparisons are done against the event's pristine _start and _end dates.
    // Returns an object with delta information and a function to undo all operations.
    // For making computations in a granularity greater than day/time, specify largeUnit.
    // NOTE: The given `newProps` might be mutated for normalization purposes.
    function mutateEvent(event, newProps, largeUnit) {
        var miscProps = {};
        var oldProps;
        var clearEnd;
        var startDelta;
        var endDelta;
        var durationDelta;
        var undoFunc;

        // diffs the dates in the appropriate way, returning a duration
        function diffDates(date1, date0) { // date1 - date0
            if (largeUnit) {
                return diffByUnit(date1, date0, largeUnit);
            }
            else if (newProps.allDay) {
                return diffDay(date1, date0);
            }
            else {
                return diffDayTime(date1, date0);
            }
        }

        newProps = newProps || {};

        // normalize new date-related properties
        if (!newProps.start) {
            newProps.start = event.start.clone();
        }
        if (newProps.end === undefined) {
            newProps.end = event.end ? event.end.clone() : null;
        }
        if (newProps.allDay == null) { // is null or undefined?
            newProps.allDay = event.allDay;
        }
        normalizeEventRange(newProps);

        // create normalized versions of the original props to compare against
        // need a real end value, for diffing
        oldProps = {
            start: event._start.clone(),
            end: event._end ? event._end.clone() : t.getDefaultEventEnd(event._allDay, event._start),
            allDay: newProps.allDay // normalize the dates in the same regard as the new properties
        };
        normalizeEventRange(oldProps);

        // need to clear the end date if explicitly changed to null
        clearEnd = event._end !== null && newProps.end === null;

        // compute the delta for moving the start date
        startDelta = diffDates(newProps.start, oldProps.start);

        // compute the delta for moving the end date
        if (newProps.end) {
            endDelta = diffDates(newProps.end, oldProps.end);
            durationDelta = endDelta.subtract(startDelta);
        }
        else {
            durationDelta = null;
        }

        // gather all non-date-related properties
        $.each(newProps, function(name, val) {
            if (isMiscEventPropName(name)) {
                if (val !== undefined) {
                    miscProps[name] = val;
                }
            }
        });

        // apply the operations to the event and all related events
        undoFunc = mutateEvents(
            clientEvents(event._id), // get events with this ID
            clearEnd,
            newProps.allDay,
            startDelta,
            durationDelta,
            miscProps
        );

        return {
            dateDelta: startDelta,
            durationDelta: durationDelta,
            undo: undoFunc
        };
    }


    // Modifies an array of events in the following ways (operations are in order):
    // - clear the event's `end`
    // - convert the event to allDay
    // - add `dateDelta` to the start and end
    // - add `durationDelta` to the event's duration
    // - assign `miscProps` to the event
    //
    // Returns a function that can be called to undo all the operations.
    //
    // TODO: don't use so many closures. possible memory issues when lots of events with same ID.
    //
    function mutateEvents(events, clearEnd, allDay, dateDelta, durationDelta, miscProps) {
        var isAmbigTimezone = t.getIsAmbigTimezone();
        var undoFunctions = [];

        // normalize zero-length deltas to be null
        if (dateDelta && !dateDelta.valueOf()) { dateDelta = null; }
        if (durationDelta && !durationDelta.valueOf()) { durationDelta = null; }

        $.each(events, function(i, event) {
            var oldProps;
            var newProps;

            // build an object holding all the old values, both date-related and misc.
            // for the undo function.
            oldProps = {
                start: event.start.clone(),
                end: event.end ? event.end.clone() : null,
                allDay: event.allDay
            };
            $.each(miscProps, function(name) {
                oldProps[name] = event[name];
            });

            // new date-related properties. work off the original date snapshot.
            // ok to use references because they will be thrown away when backupEventDates is called.
            newProps = {
                start: event._start,
                end: event._end,
                allDay: allDay // normalize the dates in the same regard as the new properties
            };
            normalizeEventRange(newProps); // massages start/end/allDay

            // strip or ensure the end date
            if (clearEnd) {
                newProps.end = null;
            }
            else if (durationDelta && !newProps.end) { // the duration translation requires an end date
                newProps.end = t.getDefaultEventEnd(newProps.allDay, newProps.start);
            }

            if (dateDelta) {
                newProps.start.add(dateDelta);
                if (newProps.end) {
                    newProps.end.add(dateDelta);
                }
            }

            if (durationDelta) {
                newProps.end.add(durationDelta); // end already ensured above
            }

            // if the dates have changed, and we know it is impossible to recompute the
            // timezone offsets, strip the zone.
            if (
                isAmbigTimezone &&
                !newProps.allDay &&
                (dateDelta || durationDelta)
            ) {
                newProps.start.stripZone();
                if (newProps.end) {
                    newProps.end.stripZone();
                }
            }

            $.extend(event, miscProps, newProps); // copy over misc props, then date-related props
            backupEventDates(event); // regenerate internal _start/_end/_allDay

            undoFunctions.push(function() {
                $.extend(event, oldProps);
                backupEventDates(event); // regenerate internal _start/_end/_allDay
            });
        });

        return function() {
            for (var i = 0; i < undoFunctions.length; i++) {
                undoFunctions[i]();
            }
        };
    }


    /* Business Hours
    -----------------------------------------------------------------------------------------*/

    t.getBusinessHoursEvents = getBusinessHoursEvents;


    // Returns an array of events as to when the business hours occur in the given view.
    // Abuse of our event system :(
    function getBusinessHoursEvents(wholeDay) {
        var optionVal = options.businessHours;
        var defaultVal = {
            className: 'fc-nonbusiness',
            start: '09:00',
            end: '17:00',
            dow: [ 1, 2, 3, 4, 5 ], // monday - friday
            rendering: 'inverse-background'
        };
        var view = t.getView();
        var eventInput;

        if (optionVal) { // `true` (which means "use the defaults") or an override object
            eventInput = $.extend(
                {}, // copy to a new object in either case
                defaultVal,
                typeof optionVal === 'object' ? optionVal : {} // override the defaults
            );
        }

        if (eventInput) {

            // if a whole-day series is requested, clear the start/end times
            if (wholeDay) {
                eventInput.start = null;
                eventInput.end = null;
            }

            return expandEvent(
                buildEventFromInput(eventInput),
                view.start,
                view.end
            );
        }

        return [];
    }


    /* Overlapping / Constraining
    -----------------------------------------------------------------------------------------*/

    t.isEventRangeAllowed = isEventRangeAllowed;
    t.isSelectionRangeAllowed = isSelectionRangeAllowed;
    t.isExternalDropRangeAllowed = isExternalDropRangeAllowed;


    function isEventRangeAllowed(range, event) {
        var source = event.source || {};
        var constraint = firstDefined(
            event.constraint,
            source.constraint,
            options.eventConstraint
        );
        var overlap = firstDefined(
            event.overlap,
            source.overlap,
            options.eventOverlap
        );

        range = ensureVisibleEventRange(range); // ensure a proper range with an end for isRangeAllowed

        return isRangeAllowed(range, constraint, overlap, event);
    }


    function isSelectionRangeAllowed(range) {
        return isRangeAllowed(range, options.selectConstraint, options.selectOverlap);
    }


    // when `eventProps` is defined, consider this an event.
    // `eventProps` can contain misc non-date-related info about the event.
    function isExternalDropRangeAllowed(range, eventProps) {
        var eventInput;
        var event;

        // note: very similar logic is in View's reportExternalDrop
        if (eventProps) {
            eventInput = $.extend({}, eventProps, range);
            event = expandEvent(buildEventFromInput(eventInput))[0];
        }

        if (event) {
            return isEventRangeAllowed(range, event);
        }
        else { // treat it as a selection

            range = ensureVisibleEventRange(range); // ensure a proper range with an end for isSelectionRangeAllowed

            return isSelectionRangeAllowed(range);
        }
    }


    // Returns true if the given range (caused by an event drop/resize or a selection) is allowed to exist
    // according to the constraint/overlap settings.
    // `event` is not required if checking a selection.
    function isRangeAllowed(range, constraint, overlap, event) {
        var constraintEvents;
        var anyContainment;
        var peerEvents;
        var i, peerEvent;
        var peerOverlap;

        // normalize. fyi, we're normalizing in too many places :(
        range = $.extend({}, range); // copy all properties in case there are misc non-date properties
        range.start = range.start.clone().stripZone();
        range.end = range.end.clone().stripZone();

        // the range must be fully contained by at least one of produced constraint events
        if (constraint != null) {

            // not treated as an event! intermediate data structure
            // TODO: use ranges in the future
            constraintEvents = constraintToEvents(constraint);

            anyContainment = false;
            for (i = 0; i < constraintEvents.length; i++) {
                if (eventContainsRange(constraintEvents[i], range)) {
                    anyContainment = true;
                    break;
                }
            }

            if (!anyContainment) {
                return false;
            }
        }

        peerEvents = t.getPeerEvents(event, range);

        for (i = 0; i < peerEvents.length; i++)  {
            peerEvent = peerEvents[i];

            // there needs to be an actual intersection before disallowing anything
            if (eventIntersectsRange(peerEvent, range)) {

                // evaluate overlap for the given range and short-circuit if necessary
                if (overlap === false) {
                    return false;
                }
                // if the event's overlap is a test function, pass the peer event in question as the first param
                else if (typeof overlap === 'function' && !overlap(peerEvent, event)) {
                    return false;
                }

                // if we are computing if the given range is allowable for an event, consider the other event's
                // EventObject-specific or Source-specific `overlap` property
                if (event) {
                    peerOverlap = firstDefined(
                        peerEvent.overlap,
                        (peerEvent.source || {}).overlap
                        // we already considered the global `eventOverlap`
                    );
                    if (peerOverlap === false) {
                        return false;
                    }
                    // if the peer event's overlap is a test function, pass the subject event as the first param
                    if (typeof peerOverlap === 'function' && !peerOverlap(event, peerEvent)) {
                        return false;
                    }
                }
            }
        }

        return true;
    }


    // Given an event input from the API, produces an array of event objects. Possible event inputs:
    // 'businessHours'
    // An event ID (number or string)
    // An object with specific start/end dates or a recurring event (like what businessHours accepts)
    function constraintToEvents(constraintInput) {

        if (constraintInput === 'businessHours') {
            return getBusinessHoursEvents();
        }

        if (typeof constraintInput === 'object') {
            return expandEvent(buildEventFromInput(constraintInput));
        }

        return clientEvents(constraintInput); // probably an ID
    }


    // Does the event's date range fully contain the given range?
    // start/end already assumed to have stripped zones :(
    function eventContainsRange(event, range) {
        var eventStart = event.start.clone().stripZone();
        var eventEnd = t.getEventEnd(event).stripZone();

        return range.start >= eventStart && range.end <= eventEnd;
    }


    // Does the event's date range intersect with the given range?
    // start/end already assumed to have stripped zones :(
    function eventIntersectsRange(event, range) {
        var eventStart = event.start.clone().stripZone();
        var eventEnd = t.getEventEnd(event).stripZone();

        return range.start < eventEnd && range.end > eventStart;
    }


    t.getEventCache = function() {
        return cache;
    };

}


// Returns a list of events that the given event should be compared against when being considered for a move to
// the specified range. Attached to the Calendar's prototype because EventManager is a mixin for a Calendar.
Calendar.prototype.getPeerEvents = function(event, range) {
    var cache = this.getEventCache();
    var peerEvents = [];
    var i, otherEvent;

    for (i = 0; i < cache.length; i++) {
        otherEvent = cache[i];
        if (
            !event ||
            event._id !== otherEvent._id // don't compare the event to itself or other related [repeating] events
        ) {
            peerEvents.push(otherEvent);
        }
    }

    return peerEvents;
};


// updates the "backup" properties, which are preserved in order to compute diffs later on.
function backupEventDates(event) {
    event._allDay = event.allDay;
    event._start = event.start.clone();
    event._end = event.end ? event.end.clone() : null;
}



/* An abstract class for the "basic" views, as well as month view. Renders one or more rows of day cells.
----------------------------------------------------------------------------------------------------------------------*/
// It is a manager for a DayGrid subcomponent, which does most of the heavy lifting.
// It is responsible for managing width/height.

var BasicView = View.extend({

    dayGrid: null, // the main subcomponent that does most of the heavy lifting

    dayNumbersVisible: false, // display day numbers on each day cell?
    weekNumbersVisible: false, // display week numbers along the side?

    weekNumberWidth: null, // width of all the week-number cells running down the side

    headRowEl: null, // the fake row element of the day-of-week header


    initialize: function() {
        this.dayGrid = new DayGrid(this);
        this.coordMap = this.dayGrid.coordMap; // the view's date-to-cell mapping is identical to the subcomponent's
    },


    // Sets the display range and computes all necessary dates
    setRange: function(range) {
        View.prototype.setRange.call(this, range); // call the super-method

        this.dayGrid.breakOnWeeks = /year|month|week/.test(this.intervalUnit); // do before setRange
        this.dayGrid.setRange(range);
    },


    // Compute the value to feed into setRange. Overrides superclass.
    computeRange: function(date) {
        var range = View.prototype.computeRange.call(this, date); // get value from the super-method

        // year and month views should be aligned with weeks. this is already done for week
        if (/year|month/.test(range.intervalUnit)) {
            range.start.startOf('week');
            range.start = this.skipHiddenDays(range.start);

            // make end-of-week if not already
            if (range.end.weekday()) {
                range.end.add(1, 'week').startOf('week');
                range.end = this.skipHiddenDays(range.end, -1, true); // exclusively move backwards
            }
        }

        return range;
    },


    // Renders the view into `this.el`, which should already be assigned
    renderDates: function() {

        this.dayNumbersVisible = this.dayGrid.rowCnt > 1; // TODO: make grid responsible
        this.weekNumbersVisible = this.opt('weekNumbers');
        this.dayGrid.numbersVisible = this.dayNumbersVisible || this.weekNumbersVisible;

        this.el.addClass('fc-basic-view').html(this.renderHtml());

        this.headRowEl = this.el.find('thead .fc-row');

        this.scrollerEl = this.el.find('.fc-day-grid-container');
        this.dayGrid.coordMap.containerEl = this.scrollerEl; // constrain clicks/etc to the dimensions of the scroller

        this.dayGrid.setElement(this.el.find('.fc-day-grid'));
        this.dayGrid.renderDates(this.hasRigidRows());
    },


    // Unrenders the content of the view. Since we haven't separated skeleton rendering from date rendering,
    // always completely kill the dayGrid's rendering.
    unrenderDates: function() {
        this.dayGrid.unrenderDates();
        this.dayGrid.removeElement();
    },


    renderBusinessHours: function() {
        this.dayGrid.renderBusinessHours();
    },


    // Builds the HTML skeleton for the view.
    // The day-grid component will render inside of a container defined by this HTML.
    renderHtml: function() {
        return '' +
            '<table>' +
                '<thead class="fc-head">' +
                    '<tr>' +
                        '<td class="' + this.widgetHeaderClass + '">' +
                            this.dayGrid.headHtml() + // render the day-of-week headers
                        '</td>' +
                    '</tr>' +
                '</thead>' +
                '<tbody class="fc-body">' +
                    '<tr>' +
                        '<td class="' + this.widgetContentClass + '">' +
                            '<div class="fc-day-grid-container">' +
                                '<div class="fc-day-grid"/>' +
                            '</div>' +
                        '</td>' +
                    '</tr>' +
                '</tbody>' +
            '</table>';
    },


    // Generates the HTML that will go before the day-of week header cells.
    // Queried by the DayGrid subcomponent when generating rows. Ordering depends on isRTL.
    headIntroHtml: function() {
        if (this.weekNumbersVisible) {
            return '' +
                '<th class="fc-week-number ' + this.widgetHeaderClass + '" ' + this.weekNumberStyleAttr() + '>' +
                    '<span>' + // needed for matchCellWidths
                        htmlEscape(this.opt('weekNumberTitle')) +
                    '</span>' +
                '</th>';
        }
    },


    // Generates the HTML that will go before content-skeleton cells that display the day/week numbers.
    // Queried by the DayGrid subcomponent. Ordering depends on isRTL.
    numberIntroHtml: function(row) {
        if (this.weekNumbersVisible) {
            return '' +
                '<td class="fc-week-number" ' + this.weekNumberStyleAttr() + '>' +
                    '<span>' + // needed for matchCellWidths
                        this.dayGrid.getCell(row, 0).start.format('w') +
                    '</span>' +
                '</td>';
        }
    },


    // Generates the HTML that goes before the day bg cells for each day-row.
    // Queried by the DayGrid subcomponent. Ordering depends on isRTL.
    dayIntroHtml: function() {
        if (this.weekNumbersVisible) {
            return '<td class="fc-week-number ' + this.widgetContentClass + '" ' +
                this.weekNumberStyleAttr() + '></td>';
        }
    },


    // Generates the HTML that goes before every other type of row generated by DayGrid. Ordering depends on isRTL.
    // Affects helper-skeleton and highlight-skeleton rows.
    introHtml: function() {
        if (this.weekNumbersVisible) {
            return '<td class="fc-week-number" ' + this.weekNumberStyleAttr() + '></td>';
        }
    },


    // Generates the HTML for the <td>s of the "number" row in the DayGrid's content skeleton.
    // The number row will only exist if either day numbers or week numbers are turned on.
    numberCellHtml: function(cell) {
        var date = cell.start;
        var classes;

        if (!this.dayNumbersVisible) { // if there are week numbers but not day numbers
            return '<td/>'; //  will create an empty space above events :(
        }

        classes = this.dayGrid.getDayClasses(date);
        classes.unshift('fc-day-number');

        return '' +
            '<td class="' + classes.join(' ') + '" data-date="' + date.format() + '">' +
                date.date() +
            '</td>';
    },


    // Generates an HTML attribute string for setting the width of the week number column, if it is known
    weekNumberStyleAttr: function() {
        if (this.weekNumberWidth !== null) {
            return 'style="width:' + this.weekNumberWidth + 'px"';
        }
        return '';
    },


    // Determines whether each row should have a constant height
    hasRigidRows: function() {
        var eventLimit = this.opt('eventLimit');
        return eventLimit && typeof eventLimit !== 'number';
    },


    /* Dimensions
    ------------------------------------------------------------------------------------------------------------------*/


    // Refreshes the horizontal dimensions of the view
    updateWidth: function() {
        if (this.weekNumbersVisible) {
            // Make sure all week number cells running down the side have the same width.
            // Record the width for cells created later.
            this.weekNumberWidth = matchCellWidths(
                this.el.find('.fc-week-number')
            );
        }
    },


    // Adjusts the vertical dimensions of the view to the specified values
    setHeight: function(totalHeight, isAuto) {
        var eventLimit = this.opt('eventLimit');
        var scrollerHeight;

        // reset all heights to be natural
        unsetScroller(this.scrollerEl);
        uncompensateScroll(this.headRowEl);

        this.dayGrid.removeSegPopover(); // kill the "more" popover if displayed

        // is the event limit a constant level number?
        if (eventLimit && typeof eventLimit === 'number') {
            this.dayGrid.limitRows(eventLimit); // limit the levels first so the height can redistribute after
        }

        scrollerHeight = this.computeScrollerHeight(totalHeight);
        this.setGridHeight(scrollerHeight, isAuto);

        // is the event limit dynamically calculated?
        if (eventLimit && typeof eventLimit !== 'number') {
            this.dayGrid.limitRows(eventLimit); // limit the levels after the grid's row heights have been set
        }

        if (!isAuto && setPotentialScroller(this.scrollerEl, scrollerHeight)) { // using scrollbars?

            compensateScroll(this.headRowEl, getScrollbarWidths(this.scrollerEl));

            // doing the scrollbar compensation might have created text overflow which created more height. redo
            scrollerHeight = this.computeScrollerHeight(totalHeight);
            this.scrollerEl.height(scrollerHeight);
        }
    },


    // Sets the height of just the DayGrid component in this view
    setGridHeight: function(height, isAuto) {
        if (isAuto) {
            undistributeHeight(this.dayGrid.rowEls); // let the rows be their natural height with no expanding
        }
        else {
            distributeHeight(this.dayGrid.rowEls, height, true); // true = compensate for height-hogging rows
        }
    },


    /* Events
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders the given events onto the view and populates the segments array
    renderEvents: function(events) {
        this.dayGrid.renderEvents(events);

        this.updateHeight(); // must compensate for events that overflow the row
    },


    // Retrieves all segment objects that are rendered in the view
    getEventSegs: function() {
        return this.dayGrid.getEventSegs();
    },


    // Unrenders all event elements and clears internal segment data
    unrenderEvents: function() {
        this.dayGrid.unrenderEvents();

        // we DON'T need to call updateHeight() because:
        // A) a renderEvents() call always happens after this, which will eventually call updateHeight()
        // B) in IE8, this causes a flash whenever events are rerendered
    },


    /* Dragging (for both events and external elements)
    ------------------------------------------------------------------------------------------------------------------*/


    // A returned value of `true` signals that a mock "helper" event has been rendered.
    renderDrag: function(dropLocation, seg) {
        return this.dayGrid.renderDrag(dropLocation, seg);
    },


    unrenderDrag: function() {
        this.dayGrid.unrenderDrag();
    },


    /* Selection
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of a selection
    renderSelection: function(range) {
        this.dayGrid.renderSelection(range);
    },


    // Unrenders a visual indications of a selection
    unrenderSelection: function() {
        this.dayGrid.unrenderSelection();
    }

});



/* A month view with day cells running in rows (one-per-week) and columns
----------------------------------------------------------------------------------------------------------------------*/

var MonthView = BasicView.extend({

    // Produces information about what range to display
    computeRange: function(date) {
        var range = BasicView.prototype.computeRange.call(this, date); // get value from super-method
        var rowCnt;

        // ensure 6 weeks
        if (this.isFixedWeeks()) {
            rowCnt = Math.ceil(range.end.diff(range.start, 'weeks', true)); // could be partial weeks due to hiddenDays
            range.end.add(6 - rowCnt, 'weeks');
        }

        return range;
    },


    // Overrides the default BasicView behavior to have special multi-week auto-height logic
    setGridHeight: function(height, isAuto) {

        isAuto = isAuto || this.opt('weekMode') === 'variable'; // LEGACY: weekMode is deprecated

        // if auto, make the height of each row the height that it would be if there were 6 weeks
        if (isAuto) {
            height *= this.rowCnt / 6;
        }

        distributeHeight(this.dayGrid.rowEls, height, !isAuto); // if auto, don't compensate for height-hogging rows
    },


    isFixedWeeks: function() {
        var weekMode = this.opt('weekMode'); // LEGACY: weekMode is deprecated
        if (weekMode) {
            return weekMode === 'fixed'; // if any other type of weekMode, assume NOT fixed
        }

        return this.opt('fixedWeekCount');
    }

});



fcViews.basic = {
    'class': BasicView
};

fcViews.basicDay = {
    type: 'basic',
    duration: { days: 1 }
};

fcViews.basicWeek = {
    type: 'basic',
    duration: { weeks: 1 }
};

fcViews.month = {
    'class': MonthView,
    duration: { months: 1 }, // important for prev/next
    defaults: {
        fixedWeekCount: true
    }
};


/* An abstract class for all agenda-related views. Displays one more columns with time slots running vertically.
----------------------------------------------------------------------------------------------------------------------*/
// Is a manager for the TimeGrid subcomponent and possibly the DayGrid subcomponent (if allDaySlot is on).
// Responsible for managing width/height.

var AgendaView = View.extend({

    timeGrid: null, // the main time-grid subcomponent of this view
    dayGrid: null, // the "all-day" subcomponent. if all-day is turned off, this will be null

    axisWidth: null, // the width of the time axis running down the side

    noScrollRowEls: null, // set of fake row elements that must compensate when scrollerEl has scrollbars

    // when the time-grid isn't tall enough to occupy the given height, we render an <hr> underneath
    bottomRuleEl: null,
    bottomRuleHeight: null,


    initialize: function() {
        this.timeGrid = new TimeGrid(this);

        if (this.opt('allDaySlot')) { // should we display the "all-day" area?
            this.dayGrid = new DayGrid(this); // the all-day subcomponent of this view

            // the coordinate grid will be a combination of both subcomponents' grids
            this.coordMap = new ComboCoordMap([
                this.dayGrid.coordMap,
                this.timeGrid.coordMap
            ]);
        }
        else {
            this.coordMap = this.timeGrid.coordMap;
        }
    },


    /* Rendering
    ------------------------------------------------------------------------------------------------------------------*/


    // Sets the display range and computes all necessary dates
    setRange: function(range) {
        View.prototype.setRange.call(this, range); // call the super-method

        this.timeGrid.setRange(range);
        if (this.dayGrid) {
            this.dayGrid.setRange(range);
        }
    },


    // Renders the view into `this.el`, which has already been assigned
    renderDates: function() {

        this.el.addClass('fc-agenda-view').html(this.renderHtml());

        // the element that wraps the time-grid that will probably scroll
        this.scrollerEl = this.el.find('.fc-time-grid-container');
        this.timeGrid.coordMap.containerEl = this.scrollerEl; // don't accept clicks/etc outside of this

        this.timeGrid.setElement(this.el.find('.fc-time-grid'));
        this.timeGrid.renderDates();

        // the <hr> that sometimes displays under the time-grid
        this.bottomRuleEl = $('<hr class="fc-divider ' + this.widgetHeaderClass + '"/>')
            .appendTo(this.timeGrid.el); // inject it into the time-grid

        if (this.dayGrid) {
            this.dayGrid.setElement(this.el.find('.fc-day-grid'));
            this.dayGrid.renderDates();

            // have the day-grid extend it's coordinate area over the <hr> dividing the two grids
            this.dayGrid.bottomCoordPadding = this.dayGrid.el.next('hr').outerHeight();
        }

        this.noScrollRowEls = this.el.find('.fc-row:not(.fc-scroller *)'); // fake rows not within the scroller
    },


    // Unrenders the content of the view. Since we haven't separated skeleton rendering from date rendering,
    // always completely kill each grid's rendering.
    unrenderDates: function() {
        this.timeGrid.unrenderDates();
        this.timeGrid.removeElement();

        if (this.dayGrid) {
            this.dayGrid.unrenderDates();
            this.dayGrid.removeElement();
        }
    },


    renderBusinessHours: function() {
        this.timeGrid.renderBusinessHours();

        if (this.dayGrid) {
            this.dayGrid.renderBusinessHours();
        }
    },


    // Builds the HTML skeleton for the view.
    // The day-grid and time-grid components will render inside containers defined by this HTML.
    renderHtml: function() {
        return '' +
            '<table>' +
                '<thead class="fc-head">' +
                    '<tr>' +
                        '<td class="' + this.widgetHeaderClass + '">' +
                            this.timeGrid.headHtml() + // render the day-of-week headers
                        '</td>' +
                    '</tr>' +
                '</thead>' +
                '<tbody class="fc-body">' +
                    '<tr>' +
                        '<td class="' + this.widgetContentClass + '">' +
                            (this.dayGrid ?
                                '<div class="fc-day-grid"/>' +
                                '<hr class="fc-divider ' + this.widgetHeaderClass + '"/>' :
                                ''
                                ) +
                            '<div class="fc-time-grid-container">' +
                                '<div class="fc-time-grid"/>' +
                            '</div>' +
                        '</td>' +
                    '</tr>' +
                '</tbody>' +
            '</table>';
    },


    // Generates the HTML that will go before the day-of week header cells.
    // Queried by the TimeGrid subcomponent when generating rows. Ordering depends on isRTL.
    headIntroHtml: function() {
        var date;
        var weekText;

        if (this.opt('weekNumbers')) {
            date = this.timeGrid.getCell(0).start;
            weekText = date.format(this.opt('smallWeekFormat'));

            return '' +
                '<th class="fc-axis fc-week-number ' + this.widgetHeaderClass + '" ' + this.axisStyleAttr() + '>' +
                    '<span>' + // needed for matchCellWidths
                        htmlEscape(weekText) +
                    '</span>' +
                '</th>';
        }
        else {
            return '<th class="fc-axis ' + this.widgetHeaderClass + '" ' + this.axisStyleAttr() + '></th>';
        }
    },


    // Generates the HTML that goes before the all-day cells.
    // Queried by the DayGrid subcomponent when generating rows. Ordering depends on isRTL.
    dayIntroHtml: function() {
        return '' +
            '<td class="fc-axis ' + this.widgetContentClass + '" ' + this.axisStyleAttr() + '>' +
                '<span>' + // needed for matchCellWidths
                    (this.opt('allDayHtml') || htmlEscape(this.opt('allDayText'))) +
                '</span>' +
            '</td>';
    },


    // Generates the HTML that goes before the bg of the TimeGrid slot area. Long vertical column.
    slotBgIntroHtml: function() {
        return '<td class="fc-axis ' + this.widgetContentClass + '" ' + this.axisStyleAttr() + '></td>';
    },


    // Generates the HTML that goes before all other types of cells.
    // Affects content-skeleton, helper-skeleton, highlight-skeleton for both the time-grid and day-grid.
    // Queried by the TimeGrid and DayGrid subcomponents when generating rows. Ordering depends on isRTL.
    introHtml: function() {
        return '<td class="fc-axis" ' + this.axisStyleAttr() + '></td>';
    },


    // Generates an HTML attribute string for setting the width of the axis, if it is known
    axisStyleAttr: function() {
        if (this.axisWidth !== null) {
             return 'style="width:' + this.axisWidth + 'px"';
        }
        return '';
    },


    /* Dimensions
    ------------------------------------------------------------------------------------------------------------------*/


    updateSize: function(isResize) {
        this.timeGrid.updateSize(isResize);

        View.prototype.updateSize.call(this, isResize); // call the super-method
    },


    // Refreshes the horizontal dimensions of the view
    updateWidth: function() {
        // make all axis cells line up, and record the width so newly created axis cells will have it
        this.axisWidth = matchCellWidths(this.el.find('.fc-axis'));
    },


    // Adjusts the vertical dimensions of the view to the specified values
    setHeight: function(totalHeight, isAuto) {
        var eventLimit;
        var scrollerHeight;

        if (this.bottomRuleHeight === null) {
            // calculate the height of the rule the very first time
            this.bottomRuleHeight = this.bottomRuleEl.outerHeight();
        }
        this.bottomRuleEl.hide(); // .show() will be called later if this <hr> is necessary

        // reset all dimensions back to the original state
        this.scrollerEl.css('overflow', '');
        unsetScroller(this.scrollerEl);
        uncompensateScroll(this.noScrollRowEls);

        // limit number of events in the all-day area
        if (this.dayGrid) {
            this.dayGrid.removeSegPopover(); // kill the "more" popover if displayed

            eventLimit = this.opt('eventLimit');
            if (eventLimit && typeof eventLimit !== 'number') {
                eventLimit = AGENDA_ALL_DAY_EVENT_LIMIT; // make sure "auto" goes to a real number
            }
            if (eventLimit) {
                this.dayGrid.limitRows(eventLimit);
            }
        }

        if (!isAuto) { // should we force dimensions of the scroll container, or let the contents be natural height?

            scrollerHeight = this.computeScrollerHeight(totalHeight);
            if (setPotentialScroller(this.scrollerEl, scrollerHeight)) { // using scrollbars?

                // make the all-day and header rows lines up
                compensateScroll(this.noScrollRowEls, getScrollbarWidths(this.scrollerEl));

                // the scrollbar compensation might have changed text flow, which might affect height, so recalculate
                // and reapply the desired height to the scroller.
                scrollerHeight = this.computeScrollerHeight(totalHeight);
                this.scrollerEl.height(scrollerHeight);
            }
            else { // no scrollbars
                // still, force a height and display the bottom rule (marks the end of day)
                this.scrollerEl.height(scrollerHeight).css('overflow', 'hidden'); // in case <hr> goes outside
                this.bottomRuleEl.show();
            }
        }
    },


    // Computes the initial pre-configured scroll state prior to allowing the user to change it
    computeInitialScroll: function() {
        var scrollTime = moment.duration(this.opt('scrollTime'));
        var top = this.timeGrid.computeTimeTop(scrollTime);

        // zoom can give weird floating-point values. rather scroll a little bit further
        top = Math.ceil(top);

        if (top) {
            top++; // to overcome top border that slots beyond the first have. looks better
        }

        return top;
    },


    /* Events
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders events onto the view and populates the View's segment array
    renderEvents: function(events) {
        var dayEvents = [];
        var timedEvents = [];
        var daySegs = [];
        var timedSegs;
        var i;

        // separate the events into all-day and timed
        for (i = 0; i < events.length; i++) {
            if (events[i].allDay) {
                dayEvents.push(events[i]);
            }
            else {
                timedEvents.push(events[i]);
            }
        }

        // render the events in the subcomponents
        timedSegs = this.timeGrid.renderEvents(timedEvents);
        if (this.dayGrid) {
            daySegs = this.dayGrid.renderEvents(dayEvents);
        }

        // the all-day area is flexible and might have a lot of events, so shift the height
        this.updateHeight();
    },


    // Retrieves all segment objects that are rendered in the view
    getEventSegs: function() {
        return this.timeGrid.getEventSegs().concat(
            this.dayGrid ? this.dayGrid.getEventSegs() : []
        );
    },


    // Unrenders all event elements and clears internal segment data
    unrenderEvents: function() {

        // unrender the events in the subcomponents
        this.timeGrid.unrenderEvents();
        if (this.dayGrid) {
            this.dayGrid.unrenderEvents();
        }

        // we DON'T need to call updateHeight() because:
        // A) a renderEvents() call always happens after this, which will eventually call updateHeight()
        // B) in IE8, this causes a flash whenever events are rerendered
    },


    /* Dragging (for events and external elements)
    ------------------------------------------------------------------------------------------------------------------*/


    // A returned value of `true` signals that a mock "helper" event has been rendered.
    renderDrag: function(dropLocation, seg) {
        if (dropLocation.start.hasTime()) {
            return this.timeGrid.renderDrag(dropLocation, seg);
        }
        else if (this.dayGrid) {
            return this.dayGrid.renderDrag(dropLocation, seg);
        }
    },


    unrenderDrag: function() {
        this.timeGrid.unrenderDrag();
        if (this.dayGrid) {
            this.dayGrid.unrenderDrag();
        }
    },


    /* Selection
    ------------------------------------------------------------------------------------------------------------------*/


    // Renders a visual indication of a selection
    renderSelection: function(range) {
        if (range.start.hasTime() || range.end.hasTime()) {
            this.timeGrid.renderSelection(range);
        }
        else if (this.dayGrid) {
            this.dayGrid.renderSelection(range);
        }
    },


    // Unrenders a visual indications of a selection
    unrenderSelection: function() {
        this.timeGrid.unrenderSelection();
        if (this.dayGrid) {
            this.dayGrid.unrenderSelection();
        }
    }

});



var AGENDA_ALL_DAY_EVENT_LIMIT = 5;

// potential nice values for the slot-duration and interval-duration
// from largest to smallest
var AGENDA_STOCK_SUB_DURATIONS = [
    { hours: 1 },
    { minutes: 30 },
    { minutes: 15 },
    { seconds: 30 },
    { seconds: 15 }
];

fcViews.agenda = {
    'class': AgendaView,
    defaults: {
        allDaySlot: true,
        allDayText: 'all-day',
        slotDuration: '00:30:00',
        minTime: '00:00:00',
        maxTime: '24:00:00',
        slotEventOverlap: true // a bad name. confused with overlap/constraint system
    }
};

fcViews.agendaDay = {
    type: 'agenda',
    duration: { days: 1 }
};

fcViews.agendaWeek = {
    type: 'agenda',
    duration: { weeks: 1 }
};


return fc; // export for Node/CommonJS
});
